JP6308123B2 - Metal powder for powder metallurgy, compound, granulated powder and sintered body - Google Patents

Description

  The present invention relates to a metal powder for powder metallurgy, a compound, a granulated powder, and a sintered body.

  In the powder metallurgy method, a composition including a metal powder and a binder is molded into a desired shape to obtain a molded body, and then the molded body is degreased and sintered to produce a sintered body. In the manufacturing process of such a sintered body, an atomic diffusion phenomenon occurs between the particles of the metal powder, and thereby the compact is gradually densified, resulting in sintering.

  For example, Patent Document 1 proposes a metal powder for powder metallurgy that includes at least one selected from the group consisting of Fe, Co, and Ni and unavoidable elements, including Zr and Si. According to such metal powder for powder metallurgy, the sinterability is improved by the action of Zr, and a high-density sintered body can be easily manufactured.

  Further, for example, in Patent Document 2, C 0.03% by weight or less, Ni 8 to 32% by weight, Cr 12 to 32% by weight, Mo 1 to 7% by weight, the balance being 100 parts by weight of stainless steel powder composed of Fe and inevitable impurities, And a metal injection molding composition characterized by comprising 0.1 to 5.5 parts by weight of one or more powders of Ti and / or Nb having an average particle size of 10 to 60 μm . By using such a composition in which two kinds of powders are mixed, a sintered body having a high sintered density and excellent corrosion resistance can be obtained.

Furthermore, for example, in Patent Document 3, C: 0.95 to 1.4 mass%, Si: 1.0 mass% or less, Mn: 1.0 mass% or less, Cr: 16 to 18 mass%, Nb: The composition includes 0.02 to 3% by mass, the balance is composed of Fe and inevitable impurities, the density after sintering is 7.65 to 7.75 g / cm ³ , and is molded by a metal injection molding method. A needle seal for a needle valve is disclosed. Thereby, a high-density needle seal is obtained.

  In recent years, the sintered body thus obtained has been widely used for various machine parts, structural parts, and the like.

  However, depending on the application of the sintered body, further densification may be required. In such a case, the density is increased by performing additional processing such as hot isostatic pressing (HIP processing) on the sintered body. The cost cannot be avoided.

  Therefore, there is an increasing expectation for the realization of a metal powder capable of producing a high-density sintered body without performing additional processing.

JP 2012-87416 A JP-A-6-279913 JP 2007-177675 A

  An object of the present invention is to provide a metal powder for metallurgy, compound and granulated powder capable of producing a high-density sintered body, and a high-density sintered body produced using the metal powder for powder metallurgy. There is.

The above object is achieved by the present invention described below.
The metal powder for powder metallurgy of the present invention is mainly composed of Fe,
Cr is contained in a ratio of 6% by mass to 32% by mass,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is included at a ratio of 0.005 mass% to 1.4 mass%,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
The second element is contained in a proportion of 0.01% by mass or more and 2% by mass or less.
The metal powder for powder metallurgy of the present invention is mainly composed of Fe,
Cr is contained in a proportion of 16% by mass or more and 27% by mass or less,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained at a ratio of 0.4 mass% to 2.5 mass%,
C is included in a proportion of 0.05% by mass or more and 0.75% by mass or less,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a proportion of 0.03% by mass or more and 0.5% by mass or less,
The second element is contained in a proportion of 0.03% by mass or more and 0.5% by mass or less.
The metal powder for powder metallurgy of the present invention is mainly composed of Fe,
Cr is contained in a proportion of 20% by mass or more and 26% by mass or less,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained in a proportion of 0.75 mass% or more and 1.75 mass% or less,
C is contained in a proportion of 0.3% by mass or more and 0.5% by mass or less,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a proportion of 0.05% by mass or more and 0.2% by mass or less,
The second element is contained in a proportion of 0.05% by mass or more and 0.2% by mass or less.

  Thereby, optimization of an alloy composition is achieved and densification at the time of sintering of the metal powder for powder metallurgy can be promoted. As a result, a metal powder for powder metallurgy capable of producing a high-density sintered body without additional processing is obtained.

The metal powder for powder metallurgy of the present invention is mainly composed of Fe,
Cr is contained in a ratio of 12% by mass to 32% by mass,
Ni is contained in a ratio of 3% by mass to 41% by mass,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is contained in a proportion of 0.005% by mass or more and 0.8% by mass or less,
Nb is contained in a ratio of 0.7% by mass or more and 2% by mass or less,
Ti, V, Y, and one element selected from the group consisting of Zr and Hf as a first element, V, Z r, 1 or element in a by periodic that are selected from the group consisting of Hf and Ta When the element in the table is larger than the first element or the element in the periodic table is the same as the first element and the element in the periodic table is larger than the first element as the second element,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
The second element is contained in a proportion of 0.01% by mass or more and 2% by mass or less.

  Thereby, optimization of an alloy composition is achieved and densification at the time of sintering of the metal powder for powder metallurgy can be promoted. As a result, a metal powder for powder metallurgy capable of producing a high-density sintered body without additional processing is obtained.

In the metal powder for powder metallurgy according to the present invention, the value obtained by dividing the content E1 of the first element by the atomic weight of the first element with respect to the value X2 obtained by dividing the content E2 of the second element by the atomic weight of the second element. The ratio X1 / X2 of X1 is preferably 0.3 or more and 3 or less.

  Thereby, when the metal powder for powder metallurgy is fired, it is possible to optimize the difference in timing between the precipitation of the first element carbide and the like and the precipitation of the second element carbide and the like. As a result, since the voids remaining in the molded body can be sequentially discharged from the inside and discharged, the voids generated in the sintered body can be minimized. Therefore, a metal powder for powder metallurgy capable of producing a sintered body having high density and excellent sintered body characteristics can be obtained.

In the metal powder for powder metallurgy according to the present invention, the total content of the first element and the content of the second element is preferably 0.05% by mass or more and 0.6% by mass or less.
As a result, the density of the sintered body to be manufactured becomes necessary and sufficient.

  The metal powder for powder metallurgy according to the present invention preferably has an austenite crystal structure.

  Thereby, high corrosion resistance and big elongation can be provided with respect to the sintered compact manufactured. That is, a metal powder for powder metallurgy capable of producing a sintered body having high corrosion resistance and large elongation despite high density is obtained.

  Thereby, the corrosion resistance of a sintered compact can be strengthened more without causing the fall of the density of the sintered compact manufactured.

  In the metal powder for powder metallurgy of the present invention, the average particle size is preferably 0.5 μm or more and 30 μm or less.

  Thereby, since the void | holes which remain | survive in a sintered compact become very few, the sintered compact which was especially high-density and excellent in the mechanical characteristic can be manufactured.

The compound of the present invention comprises the metal powder for powder metallurgy of the present invention and a binder for binding particles of the metal powder for powder metallurgy.
Thereby, the compound which can manufacture a high-density sintered compact is obtained.

The granulated powder of the present invention is obtained by granulating the metal powder for powder metallurgy of the present invention.
Thereby, the granulated powder which can manufacture a high-density sintered compact is obtained.

The sintered body of the present invention is mainly composed of Fe,
Cr is contained in a ratio of 6% by mass to 32% by mass,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is included at a ratio of 0.005 mass% to 1.4 mass%,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
It is manufactured by sintering metal powder for powder metallurgy containing the second element in a proportion of 0.01% by mass or more and 2% by mass or less.
The sintered body of the present invention is mainly composed of Fe,
Cr is contained in a ratio of 6% by mass to 32% by mass,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is included at a ratio of 0.005 mass% to 1.4 mass%,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
The second element is contained in a proportion of 0.01% by mass or more and 2% by mass or less.
The sintered body of the present invention is mainly composed of Fe,
Cr is contained in a ratio of 12% by mass to 32% by mass,
Ni is contained in a ratio of 3% by mass to 41% by mass,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is contained in a proportion of 0.005% by mass or more and 0.8% by mass or less,
Nb is contained in a ratio of 0.7% by mass or more and 2% by mass or less,
Ti, V, Y, and one element selected from the group consisting of Zr and Hf as a first element, V, Z r, 1 or element in a by periodic that are selected from the group consisting of Hf and Ta When the element in the table is larger than the first element or the element in the periodic table is the same as the first element and the element in the periodic table is larger than the first element as the second element,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
The second element is contained in a proportion of 0.01% by mass or more and 2% by mass or less.
Thereby, a high-density sintered compact is obtained, without performing an additional process.

The sintered body of the present invention, the first region preferably includes a second region lower the content of silicon oxide than the first region.

  As a result, a decrease in the oxide concentration inside the crystal and suppression of significant growth of crystal grains can be achieved, and a sintered body having a high density and excellent mechanical properties can be obtained.

  Hereinafter, the metal powder for powder metallurgy, compound, granulated powder and sintered body of the present invention will be described in detail.

[Metal powder for powder metallurgy]
First, the metal powder for powder metallurgy according to the present invention will be described.

  In powder metallurgy, a composition including a metal powder for powder metallurgy and a binder is molded into a desired shape, and then degreased and sintered to obtain a sintered body having a desired shape. Such a powder metallurgy technique has an advantage that a sintered body having a complicated and fine shape can be manufactured with a near net (a shape close to the final shape) as compared with other metallurgical techniques.

  As metal powder for powder metallurgy used for powder metallurgy, attempts have been conventionally made to increase the density of a sintered body produced by appropriately changing the composition. However, since pores are easily formed in the sintered body, it was necessary to further increase the density of the sintered body in order to obtain mechanical properties equivalent to the melted material.

  Therefore, conventionally, the obtained sintered body may be further densified by performing additional processing such as hot isostatic pressing (HIP processing). However, such additional processing involves a lot of labor and cost, and is an obstacle when expanding the use of the sintered body.

  In view of the above problems, the present inventor has intensively studied the conditions for obtaining a high-density sintered body without performing additional processing. As a result, it has been found that the density of the sintered body can be increased by optimizing the composition of the alloy constituting the metal powder, and the present invention has been completed.

  Specifically, the metal powder for powder metallurgy of the present invention contains Cr in a proportion of 6% by mass to 32% by mass, Si in a proportion of 0.3% by mass to 3% by mass, and C Is contained in a proportion of 0.005% by mass to 1.4% by mass, a first element described later is contained in a proportion of 0.01% by mass to 2% by mass, and a second element described later is 0.01%. It is a metal powder that is contained in a proportion of not less than 2% by mass and not more than 2% by mass, with the balance being composed of Fe and other elements. According to such a metal powder, as a result of optimization of the alloy composition, densification during sintering can be particularly enhanced. As a result, a high-density sintered body can be manufactured without performing additional processing.

  And the sintered compact which was excellent in mechanical characteristics will be obtained by densifying a sintered compact. Such a sintered body can be widely applied to applications in which an external force (load) is applied, such as a machine part or a structural part.

  The first element is one element selected from the group consisting of seven elements of Ti, V, Y, Zr, Nb, Hf and Ta, and the second element is the group consisting of the seven elements. And an element having a group larger than the first element in the periodic table. In addition, when the element selected as the first element and the element selected as the second element are elements of the same family in the element periodic table, an element having a period longer than the first element in the element periodic table is selected as the second element. Elemental.

  Hereinafter, the alloy composition of the metal powder for powder metallurgy according to the present invention will be described in more detail. In the following description, the metal powder for powder metallurgy may be simply referred to as “metal powder”.

(Cr)
Cr (chromium) is an element that imparts corrosion resistance to the sintered body to be produced. By using a metal powder containing Cr, a sintered body that can maintain high mechanical properties over a long period of time can be obtained.

  The Cr content in the metal powder is 6% by mass or more and 32% by mass or less, preferably 16% by mass or more and 27% by mass or less, and more preferably 20% by mass or more and 26% by mass or less. When the Cr content is less than the lower limit, depending on the overall composition, the corrosion resistance of the manufactured sintered body becomes insufficient. On the other hand, if the Cr content exceeds the upper limit, depending on the overall composition, the sinterability may be reduced, making it difficult to increase the density of the sintered body.

  In addition, the preferable range is prescribed | regulated for the content rate of Cr according to the content rate of C, Si, and Ni mentioned later.

  For example, the C content is 0.2% by mass or more and 0.7% by mass or less, the Si content is 1.5% by mass or more and 2.5% by mass or less, and the Ni content is Is 12 mass% or more and 15 mass% or less, it is preferable that especially Cr content rate is 14 mass% or more and 16 mass% or less.

  On the other hand, the C content is 0.005 mass% or more and less than 0.2 mass%, the Si content is 0.3 mass% or more and 1.5 mass% or less, and the Ni content is Is 24 mass% or more and 37 mass% or less, it is preferable that the content rate of Cr is especially 13.5 mass% or more and 17 mass% or less.

(Ni)
The metal powder for powder metallurgy of the present invention may contain Ni as necessary. Ni is an element that imparts corrosion resistance and heat resistance to the sintered body to be produced.

  The content of Ni in the metal powder is preferably 3% by mass or more and 41% by mass or less, more preferably 10% by mass or more and 39% by mass or less, and further preferably 12% by mass or more and 27% by mass or less. . By setting the Ni content within the above range, a sintered body having excellent mechanical properties over a long period of time can be obtained.

  If the Ni content is below the lower limit, depending on the overall composition, the corrosion resistance and heat resistance of the sintered body to be produced may not be sufficiently increased, while the Ni content exceeds the upper limit. When it exceeds, corrosion resistance and heat resistance may be reduced.

  In addition, the preferable range is prescribed | regulated for the content rate of Ni according to the content rate of Cr mentioned above and the content rate of C mentioned later.

  For example, when the C content is 0.48 mass% or more and 0.7 mass% or less, and the Cr content is 20 mass% or more and 22 mass% or less, the Ni content is particularly 3 mass%. The content is preferably 5% by mass or less.

(Si)
Si (silicon) is an element that imparts corrosion resistance and high mechanical properties to the sintered body to be produced. By using a metal powder containing Si, a sintered body that can maintain high mechanical properties over a long period of time is obtained. can get.

  The content of Si in the metal powder is 0.3% by mass or more and 3% by mass or less, preferably 0.4% by mass or more and 2.5% by mass or less, and more preferably 0.75% by mass or more. 1.75% by mass or less. If the Si content is lower than the lower limit value, the effect of adding Si becomes dilute depending on the overall composition, so that the corrosion resistance and mechanical properties of the sintered body to be manufactured are lowered. On the other hand, when the Si content exceeds the upper limit value, depending on the overall composition, Si becomes too much, and the corrosion resistance and mechanical properties are rather deteriorated.

(C)
C (carbon) can particularly enhance the sinterability by being used in combination with a first element and a second element described later. Specifically, each of the first element and the second element combines with C to generate a carbide. By dispersing and precipitating the carbide, an effect of preventing remarkable growth of crystal grains occurs. The clear reason why such an effect is obtained is unknown, but as one of the reasons, the dispersed precipitates become an obstacle and inhibit the remarkable growth of the crystal grains, so that the variation in the size of the crystal grains can be suppressed. It is possible. As a result, voids are less likely to occur in the sintered body, and enlargement of crystal grains is prevented, so that a sintered body having a high density and high mechanical properties can be obtained.

  The C content in the metal powder is 0.005 mass% or more and 1.4 mass% or less, preferably 0.05 mass% or more and 0.75 mass% or less, more preferably 0.3 mass%. % To 0.5 mass%. If the C content is less than the lower limit, depending on the overall composition, crystal grains are likely to grow, and the mechanical properties of the sintered body become insufficient. On the other hand, when the C content exceeds the upper limit, C increases excessively depending on the entire composition, and the sinterability deteriorates.

Hereinafter, the first element and the second element will be described in two configuration examples.
(First configuration example of the first element and the second element)
The first element and the second element precipitate carbides and oxides (hereinafter collectively referred to as “carbides and the like”). And this precipitated carbide | carbonized_material etc. are thought to inhibit the remarkable growth of a crystal grain, when a metal powder sinters. As a result, as described above, voids are less likely to occur in the sintered body, and the enlargement of crystal grains is prevented, and a sintered body having a high density and high mechanical properties can be obtained.

  In addition, as will be described in detail later, the precipitated carbides and the like promote the accumulation of silicon oxide at the grain boundaries, and as a result, the sintering is promoted and the density is increased while suppressing the enlargement of the crystal grains. .

  Incidentally, the first element and the second element are two elements selected from the group consisting of seven elements of Ti, V, Y, Zr, Nb, Hf, and Ta. It is preferable that an element belonging to Group 4A or Group 4A (Ti, Y, Zr, Hf) is included. By including an element belonging to Group 3A or 4A as at least one of the first element and the second element, oxygen contained as an oxide in the metal powder is removed, and the sinterability of the metal powder is particularly enhanced. Can do.

  Further, as described above, the first element may be one element selected from the group consisting of seven elements of Ti, V, Y, Zr, Nb, Hf and Ta, but preferably the seven elements In the group consisting of the elements, the element belongs to Group 3A or Group 4A of the long-period element periodic table. Elements belonging to Group 3A or Group 4A can remove oxygen contained in the metal powder as an oxide and can particularly enhance the sinterability of the metal powder. Thereby, the oxygen concentration remaining in the crystal grains after sintering can be reduced. As a result, the oxygen content of the sintered body can be reduced and the density can be increased. Moreover, since these elements are highly active elements, it is considered that rapid atomic diffusion is brought about. For this reason, this atomic diffusion becomes a driving force, the distance between the particles of the metal powder is efficiently reduced, and densification of the compact is promoted by forming a neck between the particles. As a result, the sintered body can be further densified.

  On the other hand, as described above, the second element is one element selected from the group consisting of seven elements of Ti, V, Y, Zr, Nb, Hf, and Ta, and the first element is Any element may be used as long as it is different, but it is preferably an element belonging to Group 5A of the periodic table of the long-period type element among the group of 7 elements. In particular, the elements belonging to Group 5A can efficiently precipitate the above-described carbides and the like, so that significant growth of crystal grains during sintering can be efficiently inhibited. As a result, the generation of fine crystal grains can be promoted, and the density of the sintered body can be increased and the mechanical properties can be improved.

  In addition, in the combination of the 1st element and 2nd element which consist of the above elements, each effect is exhibited, without mutually inhibiting. For this reason, such a metal powder containing the first element and the second element can produce a particularly high-density sintered body.

  More preferably, a combination in which the first element is an element belonging to Group 4A and the second element is Nb is employed.

More preferably, a combination in which the first element is Zr or Hf and the second element is Nb is employed.
By adopting such a combination, the above-described effect becomes more remarkable.

  Of these elements, Zr is a ferrite-forming element, so that a body-centered cubic lattice phase is precipitated. This body-centered cubic lattice phase is excellent in sinterability compared to other crystal lattice phases, and thus contributes to higher density of the sintered body.

  The content of the first element in the metal powder is 0.01% by mass or more and 2% by mass or less, preferably 0.03% by mass or more and 0.5% by mass or less, and more preferably 0.05% by mass. % To 0.2% by mass. When the content of the first element is below the lower limit, depending on the entire composition, the effect of adding the first element becomes dilute, so that the density of the sintered body to be manufactured becomes insufficient. On the other hand, if the content of the first element exceeds the upper limit, depending on the overall composition, the first element will be too much, so that the ratio of the above-described carbides will be too much, and the densification will be impaired. .

  The content of the second element in the metal powder is 0.01% by mass or more and 2% by mass or less, preferably 0.03% by mass or more and 0.5% by mass or less, more preferably 0.05% by mass. % To 0.2% by mass. If the content ratio of the second element is less than the lower limit, depending on the entire composition, the effect of adding the second element becomes dilute, so that the density of the sintered body to be manufactured becomes insufficient. On the other hand, if the content ratio of the second element exceeds the upper limit, depending on the entire composition, the second element becomes too much, so that the ratio of the above-mentioned carbides and the like becomes too large, and the densification is impaired. .

  In particular, when Nb is selected as the first element, the content is preferably 0.7% by mass or more and 2% by mass or less, and more preferably 0.8% by mass or more and 1.8% by mass or less. More preferably, it is 1.2 mass% or more and 1.5 mass% or less.

  When Nb is selected as the first element, Ta is selected as the second element. In this case, the content of the second element is the same as the content of the second element described above. In particular, it is preferably 0.05% by mass or more and 0.1% by mass or less.

  On the other hand, when Nb is selected as the second element, the content is preferably 0.7% by mass or more and 2% by mass or less, and more preferably 0.8% by mass or more and 1.8% by mass or less. More preferably, it is 1.2 mass% or more and 1.5 mass% or less.

  When Nb is selected as the second element, the first element is selected from the group consisting of five elements of Ti, V, Y, Zr, and Hf. The content is the same as the content of the first element described above, and is particularly preferably 0.05% by mass or more and 0.1% by mass or less.

  In addition, as described above, the first element and the second element each precipitate carbide or the like. However, as described above, the element belonging to the 3A group or the 4A group is selected as the first element, and the second element is described above. Thus, when an element belonging to the group 5A is selected, it is assumed that the timing at which the carbide of the first element precipitates and the timing at which the carbide of the second element precipitates are different from each other when the metal powder is sintered. . Since the timing of precipitation of carbides and the like is shifted in this way, the sintering proceeds gradually, so that it is considered that the formation of pores is suppressed and a dense sintered body can be obtained. That is, it is considered that the presence of both the first element carbide and the second element carbide makes it possible to suppress the enlargement of crystal grains while achieving higher density.

The metal powder only needs to contain two kinds of elements selected from the group consisting of the seven elements, but the elements are selected from this group and are different from the two kinds of elements. May further be included. That is, the metal powder may contain three or more elements selected from the group consisting of the seven elements. As a result, the effect described above can be further enhanced, although it differs somewhat depending on the combination.
Here, the case where Nb is selected as the second element will be particularly described.

The ratio between the content ratio of the first element and the content ratio of the second element is preferably set in consideration of the atomic weight of the element selected as the first element and the atomic weight of the element selected as the second element.

Specifically, the value obtained by dividing the content E1 (mass%) of the first element by the atomic weight of the first element is taken as an index X1, and the content E2 (mass%) of the second element is divided by the atomic weight of the second element. The ratio X1 / X2 of the index X1 with respect to the index X2 is preferably 0.01 or more and 0.3 or less, more preferably 0.02 or more and 0.25 or less. More preferably, it is 0.03 or more and 0.2 or less. By setting X1 / X2 within the above range, it is possible to optimize the difference between the timing of precipitation of the first element carbide and the like and the timing of precipitation of the second element carbide and the like. Thereby, since the void | hole remaining in a molded object can be discharged | emitted as it sweeps out sequentially from an inner side, the void | hole produced in a sintered compact can be suppressed to the minimum. Therefore, by setting X1 / X2 within the above range, a metal powder capable of producing a sintered body having high density and excellent mechanical properties can be obtained. Further, since the balance between the number of atoms of the first element and the number of atoms of the second element is optimized, the effect brought about by the first element and the effect brought about by the second element are exhibited synergistically, A sintered body having a density can be obtained.

  Here, for an example of a specific combination of the first element and the second element, the ratio E1 / E2 of the content ratio E1 (mass%) and the content ratio E2 (mass%) based on the range of the ratio X1 / X2 described above. Is also calculated.

For example, when the first element is Zr and the second element is Nb, the atomic weight of Zr is 91.2 and the atomic weight of Nb is 92.9, so E1 / E2 is 0.01 or more and 0 .29 or less is preferable, and 0.02 or more and 0.25 or less is more preferable.

When the first element is Hf and the second element is Nb, the atomic weight of Hf is 178.5 and the atomic weight of Nb is 92.9, so E1 / E2 is 0.02 or more and 0. Is preferably .58 or less, more preferably 0.04 or more and 0.48 or less.

When the first element is Ti and the second element is Nb, the atomic weight of Ti is 47.9, and the atomic weight of Nb is 92.9, so E1 / E2 is 0.01 or more and 0. Is preferably 15 or less, and more preferably 0.01 or more and 0.13 or less.

When the first element is Y and the second element is Nb, the atomic weight of Y is 88.9 and the atomic weight of Nb is 92.9, so E1 / E2 is 0.01 or more and 0. .29 or less is preferable, and 0.02 or more and 0.24 or less is more preferable.

When the first element is V and the second element is Nb, the atomic weight of V is 50.9, and the atomic weight of Nb is 92.9, so E1 / E2 is 0.01 or more and 0. .16 or less, more preferably 0.01 or more and 0.14 or less.

  Although the case where Nb is selected as the second element has been particularly described here, E1 / E2 can be calculated in the same manner as described above even when an element other than Nb is selected.

  The total (E1 + E2) of the content ratio E1 of the first element and the content ratio E2 of the second element is preferably 0.8% by mass to 2.1% by mass, and more preferably 0.9% by mass to 2% by mass. % Or less is more preferable, and 1% by mass or more and 1.8% by mass or less is further preferable. By setting the sum of the content ratio of the first element and the content ratio of the second element within the above range, it is necessary and sufficient to increase the density of the manufactured sintered body.

  When the ratio of the total content of the first element and the content of the second element to the Si content is (E1 + E2) / Si, (E1 + E2) / Si is 0.5 or more and 3 or less. Preferably, it is 0.8 or more and 2.5 or less, more preferably 1 or more and 2 or less. By setting (E1 + E2) / Si within the above range, the reduction in toughness when Si is added is sufficiently compensated by the addition of the first element and the second element. As a result, it is possible to obtain a metal powder capable of producing a sintered body having excellent mechanical properties such as toughness and excellent corrosion resistance derived from Si, despite its high density.

  In addition, by adding appropriate amounts of the first element and the second element, the carbide of the first element, the carbide of the second element, and the like become “nuclei” at the grain boundaries in the sintered body, and the silicon oxide Accumulation is thought to occur. Since silicon oxide accumulates at the crystal grain boundaries, the oxide concentration in the crystal grains decreases, so that sintering is promoted. As a result, it is considered that the densification of the sintered body is further promoted.

  Furthermore, since the precipitated silicon oxide easily moves to the triple point of the grain boundary during the accumulation process, crystal growth at this point is suppressed (pinning effect). As a result, remarkable growth of crystal grains is suppressed, and a sintered body having finer crystals can be obtained. Such a sintered body has particularly high mechanical properties.

  Further, the accumulated silicon oxide tends to be located at the triple point of the grain boundary as described above, and therefore tends to be formed into a granular shape. Therefore, the sintered body has such a granular shape, the first region having a relatively high silicon oxide content, and the second region having a relatively low silicon oxide content than the first region, Is easily formed. The presence of the first region makes it possible to reduce the oxide concentration inside the crystal and suppress the remarkable growth of crystal grains as described above.

  When qualitative quantitative analysis is performed for each of the first region and the second region using an electron beam microanalyzer (EPMA), O (oxygen) is the main element in the first region, while in the second region, Fe is the main element. As described above, the first region exists mainly in the crystal grain boundary, while the second region exists mainly in the crystal grain. Therefore, in the first region, when the sum of the content ratios of the two elements of O and Si and the content ratio of Fe are compared, the sum of the content ratios of the two elements is larger than the content ratio of Fe. On the other hand, in the second region, the sum of the contents of the two elements O and Si is overwhelmingly smaller than the content of Fe. From these facts, it is understood that Si and O are integrated in the first region. Specifically, in the first region, the sum of the Si content and the O content is 1.5 times or more the Fe content. Further, the Si content in the first region is three times or more the Si content in the second region.

  Furthermore, although it may differ depending on the composition ratio, at least one of the content ratio of the first element and the content ratio of the second element satisfies the relationship of first region> second region. This indicates that the first element carbide, the second element carbide, and the like described above serve as nuclei when silicon oxide accumulates in the first region. As a specific example, the content ratio of the first element in the first region is three times or more the content ratio of the second element in the second region.

  Note that the accumulation of silicon oxide as described above is considered to be one cause of densification of the sintered body. Therefore, even if the sintered body has been densified by the present invention, it is considered that silicon oxide may not be accumulated depending on the composition ratio. That is, depending on the composition ratio, the first region and the second region may not be included.

  Moreover, although the diameter of the 1st area | region which makes | forms granularity changes with Si content rates in the whole sintered compact, it is about 0.5 micrometer or more and 15 micrometers or less, Preferably it is about 1 micrometer or more and 10 micrometers or less. Thereby, the densification of a sintered compact can fully be accelerated | stimulated, suppressing the fall of the mechanical characteristic of the sintered compact accompanying accumulating of silicon oxide.

  Note that the diameter of the first region is obtained as an average value of the diameters of circles having the same area as the area of the first region specified from light and shade (circle equivalent diameter) in the electron micrograph of the cross section of the sintered body. it can. When the average value is obtained, 10 or more measured values are used.

  Further, when the total ratio of the content ratio of the first element and the content ratio of the second element to the content ratio of C is (E1 + E2) / C, (E1 + E2) / C is preferably 1 or more and 16 or less. 1.5 or more and 13 or less is more preferable, and 2 or more and 10 or less is more preferable. By setting (E1 + E2) / C within the above range, it is possible to achieve both an increase in hardness and a decrease in toughness when C is added and an increase in density caused by the addition of the first element and the second element. Can do. As a result, a metal powder capable of producing a sintered body having excellent mechanical properties such as tensile strength and toughness can be obtained.

(Second configuration example of the first element and the second element)
On the other hand, Nb may be omitted from the group consisting of the seven elements from which the first element and the second element are selected. This second configuration example is an example in which Nb is included as a base element, and the first element and the second element are selected from the group consisting of six elements excluding Nb from the seven elements. Hereinafter, the second configuration example will be described. In the following description, differences from the first configuration example will be mainly described, and description of similar matters will be omitted.

  The first element in this configuration example is one element selected from the group consisting of six elements of Ti, V, Y, Zr, Hf and Ta, and the second element is a group consisting of the six elements. And an element having a group larger than the first element in the periodic table. In addition, when the element selected as the first element and the element selected as the second element are elements of the same family in the element periodic table, an element having a period longer than the first element in the element periodic table is selected as the second element. Elemental.

  That is, the metal powder for powder metallurgy according to this configuration example includes Cr in a ratio of 12% by mass to 32% by mass, Ni in a ratio of 3% by mass to 40% by mass, and Si of 0.2% by mass. 3% by mass to 3% by mass, C is 0.005% by mass to 0.8% by mass, and Nb is 0.7% by mass to 2% by mass. The first element is contained in a proportion of 0.01% by mass or more and 0.5% by mass or less, the second element is contained in a proportion of 0.01% by mass or more and 0.5% by mass or less, and the balance is Fe and It is a metal powder composed of other elements. According to such a metal powder, as a result of optimization of the alloy composition, densification during sintering can be particularly enhanced. As a result, a high-density sintered body can be manufactured without performing additional processing.

  Further, as described above, the first element is one element selected from the group consisting of six elements of Ti, V, Y, Zr, Hf and Ta, and the second element is the six elements. Is an element selected from the group consisting of and having a larger group in the periodic table than the first element. In addition, when the element selected as the first element and the element selected as the second element are elements of the same family in the element periodic table, an element whose period in the element periodic table is larger than that of the first element is selected as the second element. Elemental.

  Further, the first element is preferably an element belonging to Group 3A or Group 4A of the periodic table of the long-period element among the group of 6 elements. Thereby, like the above-mentioned, the sinterability of metal powder can be improved, or rapid atomic diffusion can be brought about in metal powder. As a result, the sintered body can be further densified.

  On the other hand, the second element is preferably an element belonging to Group 5A of the periodic table of the long-period element among the group of 6 elements. Thereby, like the above-mentioned, the remarkable growth of the crystal grain at the time of sintering can be inhibited efficiently, and the densification of a sintered compact and the improvement of a mechanical characteristic can be aimed at.

  The content of the first element in the metal powder is 0.01% by mass or more and 2% by mass or less, preferably 0.03% by mass or more and 0.5% by mass or less, and more preferably 0.05% by mass. % To 0.2% by mass. When the content of the first element is below the lower limit, depending on the entire composition, the effect of adding the first element becomes dilute, so that the density of the sintered body to be manufactured becomes insufficient. On the other hand, if the content of the first element exceeds the upper limit, depending on the overall composition, the first element will be too much, so that the ratio of the above-described carbides will be too much, and the densification will be impaired. .

  The content of the second element in the metal powder is 0.01% by mass or more and 2% by mass or less, preferably 0.03% by mass or more and 0.5% by mass or less, more preferably 0.05% by mass. % To 0.2% by mass. If the content ratio of the second element is less than the lower limit, depending on the entire composition, the effect of adding the second element becomes dilute, so that the density of the sintered body to be manufactured becomes insufficient. On the other hand, if the content ratio of the second element exceeds the upper limit, depending on the entire composition, the second element becomes too much, so that the ratio of the above-mentioned carbides and the like becomes too large, and the densification is impaired. .

  The metal powder only needs to contain two kinds of elements selected from the group consisting of the six elements, but the elements are selected from this group and are different from the two kinds of elements. May further be included. That is, the metal powder may contain three or more elements selected from the group consisting of the six elements. As a result, the effect described above can be further enhanced, although it differs somewhat depending on the combination.

The ratio between the content ratio of the first element and the content ratio of the second element is preferably set in consideration of the atomic weight of the element selected as the first element and the atomic weight of the element selected as the second element. .

Specifically, the value obtained by dividing the content E1 (mass%) of the first element by the atomic weight of the first element is taken as an index X1, and the content E2 (mass%) of the second element is divided by the atomic weight of the second element. When the calculated value is index X2, the ratio X1 / X2 of index X1 to index X2 is preferably 0.3 or more and 3 or less, more preferably 0.5 or more and 2 or less, and 0.75 or more. More preferably, it is 1.3 or less. By setting X1 / X2 within the above range, it is possible to optimize the difference between the timing of precipitation of the first element carbide and the like and the timing of precipitation of the second element carbide and the like. Thereby, since the void | hole remaining in a molded object can be discharged | emitted as it sweeps out sequentially from an inner side, the void | hole produced in a sintered compact can be suppressed to the minimum. Therefore, by setting X1 / X2 within the above range, a metal powder capable of producing a sintered body having high density and excellent mechanical properties can be obtained. Further, since the balance between the number of atoms of the first element and the number of atoms of the second element is optimized, the effect brought about by the first element and the effect brought about by the second element are exhibited synergistically, A sintered body having a density can be obtained.

  Here, for an example of a specific combination of the first element and the second element, the ratio E1 / E2 of the content ratio E1 (mass%) and the content ratio E2 (mass%) based on the range of the ratio X1 / X2 described above. Is also calculated.

For example, when the first element is Ti and the second element is Zr, the atomic weight of Ti is 47.9 and the atomic weight of Zr is 91.2. Therefore, E1 / E2 is 0.16 or more and 1 Is preferably .58 or less, more preferably 0.26 or more and 1.05 or less.

When the first element is Zr and the second element is Ta, the atomic weight of Zr is 91.2 and the atomic weight of Ta is 180.9. Therefore, E1 / E2 is 0.15 or more and 1 0.51 or less, more preferably 0.25 or more and 1.01 or less.

When the first element is Zr and the second element is V, the atomic weight of Zr is 91.2 and the atomic weight of V is 50.9, so E1 / E2 is 0.54 or more and 5 .38 or less, more preferably 0.90 or more and 3.58 or less.

  In addition, E1 / E2 can be calculated in the same manner as described above for combinations other than those described above.

  The total (E1 + E2) of the content ratio E1 of the first element and the content ratio E2 of the second element is preferably 0.05% by mass or more and 0.6% by mass or less, and more preferably 0.10% by mass or more and 0.0. It is more preferably 48% by mass or less, and further preferably 0.12% by mass or more and 0.24% by mass or less. By setting the sum of the content ratio of the first element and the content ratio of the second element within the above range, it is necessary and sufficient to increase the density of the manufactured sintered body.

  Further, when the ratio of the total content of the first element and the content of the second element to the content of Si is (E1 + E2) / Si, (E1 + E2) / Si is 0.1 or more and 0.7 or less. Is more preferably 0.12 or more and 0.6 or less, and further preferably 0.15 or more and 0.5 or less. By setting (E1 + E2) / Si within the above range, the reduction in toughness when Si is added is sufficiently compensated by the addition of the first element and the second element. As a result, it is possible to obtain a metal powder capable of producing a sintered body having excellent mechanical properties such as toughness and excellent corrosion resistance derived from Si, despite its high density.

  In addition, by adding appropriate amounts of the first element and the second element, the carbide of the first element, the carbide of the second element, and the like become “nuclei” at the grain boundaries in the sintered body, and the silicon oxide Accumulation is thought to occur. Since silicon oxide accumulates at the crystal grain boundaries, the oxide concentration in the crystal grains decreases, so that sintering is promoted. As a result, it is considered that the densification of the sintered body is further promoted.

  Furthermore, since the precipitated silicon oxide easily moves to the triple point of the grain boundary during the accumulation process, crystal growth at this point is suppressed (pinning effect). As a result, remarkable growth of crystal grains is suppressed, and a sintered body having finer crystals can be obtained. Such a sintered body has particularly high mechanical properties.

  Further, the accumulated silicon oxide tends to be located at the triple point of the grain boundary as described above, and therefore tends to be formed into a granular shape. Therefore, the sintered body has such a granular shape, the first region having a relatively high silicon oxide content, and the second region having a relatively low silicon oxide content than the first region, Is easily formed. The presence of the first region makes it possible to reduce the oxide concentration inside the crystal and suppress the remarkable growth of crystal grains as described above.

  Furthermore, when the ratio of the total content of the first element and the content of the second element to the content of C is (E1 + E2) / C, (E1 + E2) / C is 0.1 or more and 1.6 or less. It is preferably 0.15 or more and 1.3 or less, more preferably 0.2 or more and 1 or less. By setting (E1 + E2) / C within the above range, it is possible to achieve both an increase in hardness and a decrease in toughness when C is added and an increase in density caused by the addition of the first element and the second element. Can do. As a result, a metal powder capable of producing a sintered body having excellent mechanical properties such as tensile strength and toughness can be obtained.

  In this configuration example, the content of Nb contained as an element serving as a base of the metal powder is preferably 0.7% by mass or more and 2% by mass or less, and 0.8% by mass or more and 1.8% by mass or less. More preferably, it is 1.2 mass% or more and 1.5 mass% or less. By setting the Nb content within the above range, the heat resistance (creep resistance, hot strength, etc.) of the sintered body can be further increased without causing a decrease in the density of the sintered body to be produced. it can.

  In this configuration example, the Cr content in the metal powder is preferably 12% by mass or more and 32% by mass or less.

  Furthermore, in the present configuration example, the C content in the metal powder is preferably 0.005% by mass or more and 0.8% by mass or less.

(Other elements)
In the above, two structural examples of the first element and the second element have been described. In common with these structural examples, the metal powder for powder metallurgy according to the present invention includes Mn, if necessary, in addition to the elements described above. At least one of Mo, W, Co, Cu, N, and S may be included. In addition, these elements may be inevitably included.

  Mn, like Si, is an element that imparts corrosion resistance and high mechanical properties to the sintered body to be produced.

  The content of Mn in the metal powder is not particularly limited, but is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.3% by mass or more and 3% by mass or less, and 0.5% More preferably, it is at least 2% by mass. By setting the Mn content within the above range, a sintered body having a high density and excellent mechanical properties can be obtained. Further, the mechanical strength can be increased while suppressing the reduction in elongation. Furthermore, an increase in brittleness at a high temperature (during red heat) can be suppressed.

  If the Mn content is less than the lower limit, depending on the overall composition, the corrosion resistance and mechanical properties of the sintered body to be produced may not be sufficiently improved, whereas the Mn content is If the upper limit is exceeded, corrosion resistance and mechanical properties may be deteriorated.

Mo is an element that enhances the corrosion resistance of the sintered body to be produced.
The content of Mo in the metal powder is not particularly limited, but is preferably 1% by mass to 4% by mass, more preferably 1.2% by mass to 3.5% by mass, and more preferably 2% by mass. More preferably, the content is 3% by mass or less. By setting the Mo content in the above range, the corrosion resistance of the sintered body can be further enhanced without causing a significant decrease in the density of the sintered body to be produced.

W is an element that enhances the heat resistance of the sintered body to be produced.
Although the content rate of W in a metal powder is not specifically limited, It is preferable that they are 1 mass% or more and 4 mass% or less, and it is more preferable that they are 2 mass% or more and 3 mass% or less. By setting the W content in the above range, the heat resistance of the sintered body can be further enhanced without causing a significant decrease in the density of the sintered body to be produced.

Co is an element that enhances the heat resistance of the sintered body to be produced.
The Co content in the metal powder is not particularly limited, but is preferably 18% by mass or more and 22% by mass or less, and more preferably 18.5% by mass or more and 21% by mass or less. By setting the content ratio of Co within the above range, the heat resistance of the sintered body can be further enhanced without causing a significant decrease in the density of the manufactured sintered body.

Cu is an element that enhances the corrosion resistance of the sintered body to be produced.
Although the content rate of Cu in a metal powder is not specifically limited, It is preferable that it is 5 mass% or less, and it is more preferable that it is 1 mass% or more and 4 mass% or less. By setting the Cu content within the above range, the corrosion resistance of the sintered body can be further enhanced without causing a significant decrease in the density of the sintered body to be produced.

N is an element that enhances mechanical properties such as yield strength of the sintered body to be produced.
The N content in the metal powder is not particularly limited, but is preferably 0.03% by mass or more and 1% by mass or less, more preferably 0.08% by mass or more and 0.5% by mass or less. More preferably, the content is 1% by mass or more and 0.3% by mass or less. By setting the N content within the above range, mechanical properties such as yield strength of the sintered body can be further enhanced without causing a significant decrease in the density of the sintered body to be produced.

  In order to manufacture the metal powder to which N is added, for example, a method using a nitrided raw material, a method of introducing nitrogen gas into the molten metal, a method of nitriding the manufactured metal powder, etc. are used. It is done.

S is an element that enhances the machinability of the sintered body to be produced.
Although the content rate of S in a metal powder is not specifically limited, It is preferable that it is 0.5 mass% or less, and it is more preferable that it is 0.01 mass% or more and 0.3 mass% or less. By setting the S content within the above range, the machinability of the manufactured sintered body can be further improved without causing a significant decrease in the density of the manufactured sintered body.

  In addition, B, Se, Te, Pd, Al, etc. may be added to the metal powder for powder metallurgy of the present invention. In that case, the content of these elements is not particularly limited, but is preferably less than 0.1% by mass, and preferably less than 0.2% by mass in total. In addition, these elements may be inevitably included.

  Furthermore, the metal powder for powder metallurgy of the present invention may contain impurities. Examples of the impurities include all elements other than the elements described above. Specifically, for example, Li, Be, Na, Mg, P, K, Ca, Sc, Zn, Ga, Ge, Ag, In, Sn , Sb, Os, Ir, Pt, Au, Bi and the like. The mixing amount of these impurities is preferably set so that each element is less than the contents of Fe, Cr, Si, C, the first element and the second element. The amount of these impurities mixed is preferably set so that each element is less than 0.03% by mass, and more preferably set to be less than 0.02% by mass. Further, the total amount is preferably less than 0.3% by mass, and more preferably less than 0.2% by mass. In addition, as long as the content rate is in the above range, these elements may be intentionally added because the effects as described above are not inhibited.

  On the other hand, O (oxygen) may be added intentionally or inevitably mixed, but the amount is preferably about 0.8% by mass or less, and about 0.5% by mass or less. More preferably. By keeping the amount of oxygen in the metal powder at this level, the sinterability becomes high, and a sintered body having a high density and excellent mechanical properties can be obtained. The lower limit is not particularly set, but is preferably 0.03% by mass or more from the viewpoint of ease of mass production.

  Fe is a component (main component) having the highest content ratio among the alloys constituting the metal powder for powder metallurgy of the present invention, and has a great influence on the properties of the sintered body. Although the content rate of Fe is not specifically limited, It is preferable that it is 50 mass% or more.

  The composition ratio of the metal powder for powder metallurgy is, for example, iron and steel-atomic absorption spectrophotometry specified in JIS G 1257 (2000), iron and steel-ICP emission spectroscopy specified in JIS G 1258 (2007). Analytical method, iron and steel as defined in JIS G 1253 (2002), spark discharge optical emission spectrometry, iron and steel as defined in JIS G 1256 (1997), fluorescent X-ray analysis, JIS G 1211-G 1237 Can be specified by the weight, titration, absorptiometry, etc. defined in the above. Specifically, for example, a solid emission spectroscopic analyzer manufactured by SPECTRO (spark discharge optical spectroscopic analyzer, model: SPECTROLAB, type: LAVMB08A) and an ICP apparatus (CIROS120 type) manufactured by Rigaku Corporation are exemplified.

JIS G 1211 to G 1237 are as follows.
JIS G 1211 (2011) Iron and steel-carbon determination method JIS G 1212 (1997) Iron and steel-silicon determination method JIS G 1213 (2001) Manganese determination method in iron and steel JIS G 1214 (1998) Iron and steel -Phosphorus determination method JIS G 1215 (2010) Iron and steel-sulfur determination method JIS G 1216 (1997) Iron and steel-nickel determination method JIS G 1217 (2005) Iron and steel-chromium determination method JIS G 1218 (1999) Iron And steel-molybdenum determination method JIS G 1219 (1997) Iron and steel-copper determination method JIS G 1220 (1994) Iron and steel-tungsten determination method JIS G 1221 (1998) Iron and steel-vanadium determination method JIS G 1222 (1999) ) Iron and steel-Cobalt determination method JIS G 1223 (1997) Iron and steel-titanium determination method JIS G 1224 (2001) Aluminum and iron in steel determination method JIS G 1225 (2006) Iron and steel-arsenic determination method JIS G 1226 (1994) Iron and steel Tin determination method JIS G 1227 (1999) Boron determination method in iron and steel JIS G 1228 (2006) Iron and steel-nitrogen determination method JIS G 1229 (1994) Steel-lead determination method JIS G 1232 (1980) In steel JIS G 1233 (1994) Steel-selenium quantification method JIS G 1234 (1981) Tellurium quantification method in steel JIS G 1235 (1981) Antimony quantification method in iron and steel JIS G 1236 (1992) Tantalum determination method JIS G 1237 ( 1997) Iron and steel-niobium determination method

  Further, when specifying C (carbon) and S (sulfur), in particular, an oxygen stream combustion (high frequency induction furnace combustion) -infrared absorption method defined in JIS G 1211 (2011) is also used. Specifically, a carbon / sulfur analyzer manufactured by LECO, CS-200 may be mentioned.

  Furthermore, when specifying N (nitrogen) and O (oxygen), in particular, a method for determining nitrogen in iron and steel specified in JIS G 1228 (2006), oxygen in a metal material specified in JIS Z 2613 (2006). A quantitative method is also used. Specific examples include an oxygen / nitrogen analyzer manufactured by LECO, TC-300 / EF-300.

  The metal powder for powder metallurgy of the present invention preferably has an austenite crystal structure. The crystal structure of austenite gives high elongation to the sintered body as well as high corrosion resistance. For this reason, the metal powder for powder metallurgy having such a crystal structure can produce a sintered body having high corrosion resistance and large elongation even though it has a high density.

  Whether or not the metal powder for powder metallurgy has an austenite crystal structure can be determined by, for example, an X-ray diffraction method.

  The average particle size of the metal powder for powder metallurgy of the present invention is preferably 0.5 μm or more and 30 μm or less, more preferably 1 μm or more and 20 μm or less, and further preferably 2 μm or more and 10 μm or less. By using the metal powder for powder metallurgy having such a particle size, the number of voids remaining in the sintered body is extremely reduced, and thus a sintered body having a particularly high density and excellent mechanical properties can be produced. .

  The average particle size is obtained as the particle size when the cumulative amount is 50% from the small diameter side in the cumulative particle size distribution on a mass basis obtained by the laser diffraction method.

  In addition, when the average particle size of the metal powder for powder metallurgy is below the lower limit value, there is a possibility that the moldability is lowered when forming a shape that is difficult to mold, and the sintered density is lowered, and the upper limit value is exceeded. In this case, the gap between the particles becomes large at the time of molding, so that the sintered density may also be lowered.

  The particle size distribution of the metal powder for powder metallurgy is preferably as narrow as possible. Specifically, when the average particle size of the metal powder for powder metallurgy is within the above range, the maximum particle size is preferably 200 μm or less, and more preferably 150 μm or less. By controlling the maximum particle size of the metal powder for powder metallurgy within the above range, the particle size distribution of the metal powder for powder metallurgy can be narrowed, and the density of the sintered body can be further increased.

  The maximum particle size refers to the particle size when the cumulative amount is 99.9% from the small diameter side in the cumulative particle size distribution on a mass basis obtained by the laser diffraction method.

  Further, when the short diameter of the metal powder metal powder powder powder is S [μm] and the long diameter is L [μm], the average aspect ratio defined by S / L is about 0.4 or more and 1 or less. It is preferable that it is about 0.7 or more and 1 or less. Since the metal powder for powder metallurgy having such an aspect ratio has a shape that is relatively close to a spherical shape, the filling rate when formed is increased. As a result, the sintered body can be further densified.

  The major axis is the maximum length that can be taken in the projected image of the particle, and the minor axis is the maximum length that can be taken in the direction orthogonal to the major axis. Moreover, the average value of aspect ratio is calculated | required as an average value of the value of the aspect ratio measured about 100 or more particle | grains.

Moreover, the tap density of the metal powder for powder metallurgy of the present invention is preferably 3.5 g / cm ³ or more, more preferably 4 g / cm ³ or more. When the metal powder for powder metallurgy has such a large tap density, the filling property between the particles is particularly high when obtaining a compact. For this reason, a particularly dense sintered body can be finally obtained.

The specific surface area of the metal powder for powder metallurgy of the present invention is not particularly limited, but is preferably 0.1 m ² / g or more, and more preferably 0.2 m ² / g or more. Thus, if it is a metal powder for powder metallurgy with a large specific surface area, since surface activity (surface energy) will become high, it can sinter easily even if provision of less energy. Therefore, when the molded body is sintered, a difference in sintering speed hardly occurs between the inside and the outside of the molded body, and it is possible to suppress a decrease in the sintered density due to remaining voids on the inside. .

[Method for producing sintered body]
Next, a method for producing a sintered body using such metal powder for powder metallurgy according to the present invention will be described.

  The method for producing a sintered body includes [A] a composition preparation step for preparing a composition for producing a sintered body, [B] a molding step for producing a molded body, and [C] a degreasing step for performing a degreasing treatment. And [D] a firing step for firing. Hereinafter, each process will be described sequentially.

[A] Composition Preparation Step First, the metal powder for powder metallurgy of the present invention and a binder are prepared and kneaded with a kneader to obtain a kneaded product.

  In the kneaded product (the embodiment of the compound of the present invention), the metal powder for powder metallurgy is uniformly dispersed.

  The metal powder for powder metallurgy of the present invention is produced by various powdering methods such as an atomizing method (for example, a water atomizing method, a gas atomizing method, a high-speed rotating water atomizing method, etc.), a reduction method, a carbonyl method, and a pulverizing method. .

  Among these, the metal powder for powder metallurgy of the present invention is preferably manufactured by an atomizing method, and more preferably manufactured by a water atomizing method or a high-speed rotating water atomizing method. The atomizing method is a method for producing a metal powder by causing molten metal (molten metal) to collide with a fluid (liquid or gas) jetted at high speed, thereby pulverizing and cooling the molten metal. By producing metal powder for powder metallurgy by such an atomizing method, extremely fine powder can be produced efficiently. Moreover, the particle shape of the obtained powder becomes close to a spherical shape due to the effect of surface tension. For this reason, a thing with a high filling rate is obtained when shape | molding. That is, a powder capable of producing a high-density sintered body can be obtained.

In addition, when the water atomizing method is used as the atomizing method, the pressure of water sprayed toward the molten metal (hereinafter referred to as “atomized water”) is not particularly limited, but is preferably 75 MPa or more and 120 MPa or less (750 kgf). / Cm ² or more and 1200 kgf / cm ² or less), more preferably 90 MPa or more and 120 MPa or less (900 kgf / cm ² or more and 1200 kgf / cm ² or less).

  The temperature of the atomized water is not particularly limited, but is preferably about 1 ° C. or higher and 20 ° C. or lower.

  Furthermore, atomized water is often sprayed in a conical shape having an apex on the molten metal drop path and the outer diameter gradually decreasing downward. In this case, the apex angle θ of the cone formed by the atomized water is preferably about 10 ° to 40 °, more preferably about 15 ° to 35 °. Thereby, the metal powder for powder metallurgy having the composition as described above can be reliably produced.

  Moreover, according to the water atomization method (especially high-speed rotation water flow atomization method), a molten metal can be cooled especially rapidly. For this reason, a high quality powder is obtained in a wide alloy composition.

Further, the cooling rate when the molten metal is cooled in the atomizing method is preferably 1 × 10 ⁴ ° C./s or more, and more preferably 1 × 10 ⁵ ° C./s or more. Such rapid cooling provides a homogeneous metal powder for powder metallurgy. As a result, a high-quality sintered body can be obtained.

  In addition, you may classify with respect to the metal powder for powder metallurgy obtained in this way as needed. Examples of classification methods include sieving classification, inertia classification, dry classification such as centrifugal classification, and wet classification such as sedimentation classification.

  On the other hand, examples of the binder include polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymers, acrylic resins such as polymethyl methacrylate and polybutyl methacrylate, styrene resins such as polystyrene, polyvinyl chloride, and polyvinylidene chloride. Various resins such as polyesters such as polyamide, polyethylene terephthalate, polybutylene terephthalate, polyether, polyvinyl alcohol, polyvinylpyrrolidone or copolymers thereof, various waxes, paraffin, higher fatty acids (eg stearic acid), higher alcohols, Examples include various organic binders such as higher fatty acid esters and higher fatty acid amides. Among these, one kind or a mixture of two or more kinds can be used.

  Further, the content of the binder is preferably about 2% by mass or more and 20% by mass or less, more preferably about 5% by mass or more and 10% by mass or less of the entire kneaded product. When the content of the binder is within the above range, a molded body can be formed with good moldability, the density can be increased, and the shape stability of the molded body can be made particularly excellent. This also optimizes the difference in size between the molded body and the degreased body, the so-called shrinkage rate, and prevents the dimensional accuracy of the finally obtained sintered body from being lowered. That is, a sintered body with high density and high dimensional accuracy can be obtained.

  Moreover, a plasticizer may be added to the kneaded material as necessary. Examples of the plasticizer include phthalic acid esters (eg, DOP, DEP, DBP), adipic acid esters, trimellitic acid esters, sebacic acid esters, and the like, and one or more of these are mixed. Can be used.

  Furthermore, in addition to the metal powder for powder metallurgy, the binder, and the plasticizer, various additives such as a lubricant, an antioxidant, a degreasing accelerator, and a surfactant may be added to the kneaded material as necessary. it can.

  The kneading conditions vary depending on various conditions such as the metal composition and particle size of the metal powder for powder metallurgy used, the composition of the binder, and the blending amount thereof. For example, kneading temperature: 50 ° C. or more and 200 ° C. Or less, kneading time: about 15 minutes or more and 210 minutes or less.

  Further, the kneaded product is formed into pellets (small lumps) as necessary. The particle size of the pellet is, for example, about 1 mm to 15 mm.

  Depending on the molding method described later, a granulated powder may be produced instead of the kneaded product. These kneaded materials, granulated powders, and the like are examples of compositions that are subjected to the molding step described later.

  In the embodiment of the granulated powder of the present invention, the metal powder for powder metallurgy of the present invention is granulated to bind a plurality of metal particles with a binder.

  Examples of the binder used in the production of the granulated powder include polyolefins such as polyethylene, polypropylene and ethylene-vinyl acetate copolymer, acrylic resins such as polymethyl methacrylate and polybutyl methacrylate, styrene resins such as polystyrene, Various resins such as polyesters such as vinyl chloride, polyvinylidene chloride, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyether, polyvinyl alcohol, polyvinyl pyrrolidone or copolymers thereof, various waxes, paraffin, higher fatty acids (eg, stearin) Acid), higher alcohols, higher fatty acid esters, higher fatty acid amides, and other organic binders. Among these, one or a mixture of two or more can be used.

  Among these, as a binder, what contains polyvinyl alcohol or polyvinylpyrrolidone is preferable. Since these binder components have high binding properties, a granulated powder can be efficiently formed even in a relatively small amount. In addition, since it has high thermal decomposability, it can be reliably decomposed and removed in a short time during degreasing and firing.

  Further, the content of the binder is preferably about 0.2% by mass or more and 10% by mass or less, more preferably about 0.3% by mass or more and 5% by mass or less of the whole granulated powder. More preferably, it is 3 mass% or more and 2 mass% or less. When the content of the binder is within the above range, the granulated powder is efficiently formed while suppressing remarkably large particles from being granulated or from leaving a large amount of non-granulated metal particles. be able to. Moreover, since the moldability is improved, the shape stability of the molded body can be made particularly excellent. In addition, by setting the binder content within the above range, the difference in size between the molded body and the degreased body, the so-called shrinkage rate, is optimized to prevent the dimensional accuracy of the finally obtained sintered body from being lowered. can do.

  Furthermore, various additives, such as a plasticizer, a lubricant, an antioxidant, a degreasing accelerator, and a surfactant, may be added to the granulated powder as necessary.

  On the other hand, examples of the granulation treatment include a spray drying (spray drying) method, a rolling granulation method, a fluidized bed granulation method, and a rolling fluidization granulation method.

  In the granulation treatment, a solvent that dissolves the binder is used as necessary. Examples of such solvents include water, inorganic solvents such as carbon tetrachloride, ketone solvents, alcohol solvents, ether solvents, cellosolve solvents, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, aromatic solvents. Organic solvent such as aromatic heterocyclic compound solvent, amide solvent, halogen compound solvent, ester solvent, amine solvent, nitrile solvent, nitro solvent, aldehyde solvent, etc. are selected from these One kind or a mixture of two or more kinds is used.

  The average particle size of the granulated powder is not particularly limited, but is preferably about 10 to 200 μm, more preferably about 20 to 100 μm, and more preferably about 25 to 60 μm. The granulated powder having such a particle size has good fluidity and can more accurately reflect the shape of the mold.

  The average particle size is obtained as the particle size when the cumulative amount is 50% from the small diameter side in the cumulative particle size distribution on a mass basis obtained by the laser diffraction method.

[B] Molding Step Next, the kneaded product or the granulated powder is molded to produce a molded body having the same shape as the intended sintered body.

  The production method (molding method) of the molded body is not particularly limited. For example, various molding methods such as a compacting (compression molding) method, a metal powder injection molding (MIM) method, and an extrusion molding method are used. Can be used.

Among these, the molding conditions in the case of the compacting method vary depending on various conditions such as the composition and particle size of the metal powder for powder metallurgy used, the composition of the binder, and the blending amount thereof, but the molding pressure is 200 MPa or more and 1000 MPa or less. It is preferably about (2 t / cm ² or more and 10 t / cm ² or less).

Further, although the molding conditions in the metal powder injection molding method vary depending on various conditions, the material temperature is about 80 ° C. to 210 ° C., and the injection pressure is 50 MPa to 500 MPa (0.5 t / cm ^{2 to} 5 t / cm ^2). The following is preferable.

In addition, although the molding conditions in the extrusion molding method vary depending on various conditions, the material temperature is about 80 ° C. to 210 ° C., and the extrusion pressure is 50 MPa to 500 MPa (0.5 t / cm ^{2 to} 5 t / cm ² ). It is preferable that it is about.

  The molded body thus obtained is in a state where the binder is uniformly distributed in the gaps between the plurality of particles of the metal powder.

  In addition, the shape dimension of the molded object produced is determined in consideration of the shrinkage | contraction part of the molded object in a subsequent degreasing process and a baking process.

[C] Degreasing process Next, the obtained molded body is subjected to a degreasing treatment (debinding treatment) to obtain a degreased body.

  Specifically, the molded body is heated to decompose the binder, thereby removing the binder from the molded body and performing a degreasing process.

  Examples of the degreasing treatment include a method of heating the molded body, a method of exposing the molded body to a gas that decomposes the binder, and the like.

  When using the method of heating the molded body, the heating condition of the molded body is preferably about 100 ° C. or higher and 750 ° C. or lower × 0.1 hour or longer and 20 hours or shorter, although it varies slightly depending on the composition and blending amount of the binder. 150 ° C. or more and 600 ° C. or less × 0.5 hours or more and 15 hours or less is more preferable. Thereby, degreasing | defatting of a molded object can be performed sufficiently and necessary, without sintering a molded object. As a result, it is possible to reliably prevent a large amount of binder component from remaining inside the degreased body.

  The atmosphere for heating the molded body is not particularly limited, and is a reducing gas atmosphere such as hydrogen, an inert gas atmosphere such as nitrogen or argon, an oxidizing gas atmosphere such as air, or these atmospheres. The reduced pressure atmosphere etc. which reduced pressure is mentioned.

On the other hand, examples of the gas that decomposes the binder include ozone gas.
In addition, such a degreasing process is performed by dividing into a plurality of processes (steps) having different degreasing conditions, so that the binder in the molded body can be decomposed and removed more quickly and not to remain in the molded body. Can do.

  Moreover, you may make it perform machining, such as cutting, grinding | polishing, and cutting | disconnection with respect to a degreased body as needed. Since the degreased body is relatively low in hardness and relatively rich in plasticity, it can be easily machined while preventing the shape of the degreased body from collapsing. According to such machining, a sintered body with high dimensional accuracy can be easily obtained finally.

[D] Firing step The degreased body obtained in the step [C] is fired in a firing furnace to obtain a sintered body.

  By this sintering, the metal powder for powder metallurgy is diffused at the interface between the particles, resulting in sintering. At this time, the degreased body is quickly sintered by the mechanism described above. As a result, an entirely dense and dense sintered body can be obtained.

  The firing temperature varies depending on the composition, particle size and the like of the metal powder for powder metallurgy used for the production of the molded body and the degreased body, but is set to about 980 ° C. or higher and 1330 ° C. or lower as an example. The temperature is preferably about 1050 ° C. or higher and 1260 ° C. or lower.

  The firing time is 0.2 hours or more and 7 hours or less, and preferably 1 hour or more and 6 hours or less.

  In the firing step, the sintering temperature or a firing atmosphere described later may be changed during the firing process.

  By setting the firing conditions in such a range, it is possible to sufficiently sinter the entire degreased body while preventing the sintering from proceeding excessively to cause oversintering to enlarge the crystal structure. As a result, a sintered body having a high density and particularly excellent mechanical properties can be obtained.

  Moreover, since the firing temperature is relatively low, the heating temperature in the firing furnace can be easily controlled, and thus the temperature of the degreased body is also likely to be constant. As a result, a more uniform sintered body can be produced.

  Furthermore, since the firing temperature as described above is a firing temperature that can be sufficiently realized in a general firing furnace, an inexpensive firing furnace can be used and a running cost can be suppressed. In other words, when the firing temperature is exceeded, it is necessary to use an expensive firing furnace using a special heat-resistant material, and the running cost may be increased.

  Further, the atmosphere during firing is not particularly limited, but in consideration of preventing significant oxidation of the metal powder, a reducing gas atmosphere such as hydrogen, an inert gas atmosphere such as argon, or these atmospheres The reduced pressure atmosphere etc. which reduced pressure is preferably used.

  The sintered body thus obtained has a high density and excellent mechanical properties. That is, a sintered body produced by molding a composition containing the metal powder for powder metallurgy of the present invention and a binder and then degreasing and sintering the sintered body is obtained by sintering a conventional metal powder. The relative density is higher than Therefore, according to the present invention, a high-density sintered body that could not be reached without additional processing such as HIP processing can be realized without additional processing.

  Specifically, according to the present invention, although it varies slightly depending on the composition of the metal powder for powder metallurgy, an improvement in relative density of 2% or more can be expected as an example.

  As a result, the relative density of the obtained sintered body can be expected to be 97% or more as an example (preferably 98% or more, more preferably 98.5% or more). A sintered body having a relative density in such a range is excellent in mechanical properties comparable to a smelting material, although it has a shape that is almost as close as the target shape by using powder metallurgy technology. Since it has characteristics, it can be applied to various machine parts and structural parts with little post-processing.

  In addition, the sintered body produced by molding, degreasing and sintering the composition containing the metal powder for powder metallurgy of the present invention and the binder has the conventional tensile strength and 0.2% proof stress. It becomes larger than the tensile strength and 0.2% proof stress of the sintered body similarly sintered using metal powder. This is presumably because the alloy composition was optimized to enhance the sinterability of the metal powder and the mechanical properties of the sintered body produced thereby were improved.

  Further, the sintered body manufactured as described above has a high hardness surface. Specifically, the surface Vickers hardness is expected to be 140 or more and 500 or less as an example, although it varies slightly depending on the composition of the metal powder for powder metallurgy. Further, it is expected to be preferably 150 or more and 400 or less. The sintered body having such hardness has particularly high durability.

  Note that the sintered body has a sufficiently high density and mechanical properties without any additional treatment, but various additional treatments are required to further increase the density and improve the mechanical properties. You may make it give.

  This additional process may be, for example, an additional process for increasing the density as in the HIP process described above, or may be various quenching processes, various sub-zero processes, various tempering processes, or the like. These additional processes may be performed independently or may be performed in combination.

  In the above-described firing step and various additional treatments, the light element in the metal powder (in the sintered body) volatilizes, and the composition of the finally obtained sintered body slightly changes from the composition in the metal powder. Sometimes it is.

  For example, although C varies depending on the process conditions and processing conditions, the content in the final sintered body is within the range of 5% to 100% of the content in the metal powder for powder metallurgy (preferably 30). % In the range of not less than 100% and not more than 100%).

  O also varies depending on process conditions and processing conditions, but the content in the final sintered body is in the range of 1% to 50% of the content in the metal powder for powder metallurgy (preferably 3 % In the range of not less than 50% and not more than 50%).

  On the other hand, as described above, the manufactured sintered body may be subjected to the HIP process as part of an additional process performed as necessary. However, even if the HIP process is performed, a sufficient effect may not be exhibited. Many. In the HIP process, the sintered body can be further densified, but the sintered body obtained by the present invention has already been sufficiently densified at the end of the firing step. For this reason, even if the HIP process is further performed, it is difficult to further increase the density.

  In addition, in the HIP process, it is necessary to pressurize the object to be processed through a pressure medium, so that the object to be processed is contaminated, or the composition and physical properties of the object to be processed are unintentionally changed due to the contamination. There is a possibility that the object to be treated may be discolored due to contamination. Further, when the pressure is applied, residual stress is generated or increased in the object to be processed, and as this is released over time, there is a risk of causing problems such as deformation and a decrease in dimensional accuracy.

  On the other hand, according to the present invention, since a sufficiently high density sintered body can be manufactured without performing such HIP treatment, the same high density and high strength as in the case of performing HIP treatment. It is possible to obtain a sintered body that has been made into a uniform shape. Such a sintered body has less contamination, discoloration, unintended composition and change in physical properties, etc., and less defects such as deformation and deterioration of dimensional accuracy. Therefore, according to the present invention, a sintered body having high mechanical strength and dimensional accuracy and excellent durability can be efficiently produced.

  In addition, the sintered body produced according to the present invention requires almost no additional treatment for the purpose of improving mechanical properties, and therefore the composition and crystal structure are likely to be uniform throughout the sintered body. For this reason, structural isotropy is high, and it becomes the thing excellent in the durability with respect to the load from all directions irrespective of a shape.

  In the sintered body manufactured in this way, it is recognized that the porosity in the vicinity of the surface is often relatively smaller than the porosity in the interior. The reason for this is not clear, but it can be mentioned that the addition of the first element and the second element makes it easier for the sintering reaction to proceed in the vicinity of the surface than in the molded body. .

  Specifically, when the porosity A1 near the surface of the sintered body and the porosity inside the sintered body is A2, A2-A1 is preferably 0.5% or more and 10% or less. It is more preferably 1% or more and 5% or less. A sintered body in which A2-A1 is in such a range has the necessary and sufficient mechanical strength, while allowing the surface to be easily flattened. That is, a surface having high specularity can be obtained by polishing the surface of the sintered body.

  Such a highly specular sintered body has not only high mechanical strength but also excellent aesthetics. For this reason, this sintered compact is used suitably also for the use as which the outstanding aesthetic appearance is requested | required.

  Note that the porosity A1 in the vicinity of the surface of the sintered body refers to a porosity within a range of a radius of 25 μm centering on a position at a depth of 50 μm from the surface in the cross section of the sintered body. Further, the porosity A2 inside the sintered body refers to a porosity within a range of a radius of 25 μm around a position of a depth of 300 μm from the surface in the cross section of the sintered body. These porosity ratios are values obtained by observing the cross section of the sintered body with a scanning electron microscope and dividing the area of the pores existing in the range by the area of the range.

  As mentioned above, although the metal powder for powder metallurgy, compound, granulated powder, and sintered compact of this invention were demonstrated based on suitable embodiment, this invention is not limited to these.

  In addition, the sintered body of the present invention includes, for example, parts for transportation equipment such as parts for automobiles, parts for bicycles, parts for railway vehicles, parts for ships, parts for aircraft, parts for space transport aircraft (for example, rockets). , Parts for electronic devices such as parts for personal computers, parts for mobile phones, parts for electrical equipment such as refrigerators, washing machines, air conditioners, machine parts such as machine tools and semiconductor manufacturing equipment, nuclear power plants, It is used for plant parts such as thermal power plants, hydroelectric power plants, refineries, chemical complexes, clock parts, metal tableware, jewelry, decorative items such as eyeglass frames, and all structural parts.

Next, examples of the present invention will be described.
1. Production of sintered body (Zr-Nb system) (Sample No. 1)
[1] First, a metal powder having the composition shown in Table 1 manufactured by the water atomization method was prepared. The average particle size of this metal powder was 6.05 μm.

  The powder composition shown in Table 1 was identified and quantified by inductively coupled plasma emission spectrometry (ICP analysis). For ICP analysis, an ICP device (CIROS120 type) manufactured by Rigaku Corporation was used. For carbon identification and quantification, a carbon / sulfur analyzer (CS-200) manufactured by LECO was used. Further, an oxygen / nitrogen analyzer (TC-300 / EF-300) manufactured by LECO was used for identification and quantification of O.

  [2] Next, the metal powder and a mixture of polypropylene and wax (organic binder) were weighed and mixed so that the mass ratio was 9: 1 to obtain a mixed raw material.

[3] Next, the mixed raw material was kneaded with a kneader to obtain a compound.
[4] Next, this compound was molded by an injection molding machine under the molding conditions shown below to produce a molded body.

<Molding conditions>
-Material temperature: 150 ° C
Injection pressure: 11 MPa (110 kgf / cm ² )

  [5] Next, the obtained molded body was subjected to heat treatment (degreasing treatment) under the following degreasing conditions to obtain a degreased body.

<Degreasing conditions>
・ Degreasing temperature: 500 ° C
・ Degreasing time: 1 hour (holding time at degreasing temperature)
・ Degreasing atmosphere: Nitrogen atmosphere

  [6] Next, the obtained degreased body was fired under the firing conditions shown below. This obtained the sintered compact. The shape of the sintered body was a cylindrical shape having a diameter of 10 mm and a thickness of 5 mm.

<Baking conditions>
・ Baking temperature: 1300 ℃
-Firing time: 3 hours (holding time at the firing temperature)
・ Baking atmosphere: Argon atmosphere

(Sample Nos. 2 to 26)
Except for changing the composition and the like of the metal powder for powder metallurgy as shown in Table 1, each sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1. Sample No. About 26 sintered compacts, the HIP process was performed on the following conditions after baking. Sample No. The sintered bodies 12 to 14 and 25 are obtained by using metal powders produced by the gas atomizing method. In Table 1, “gas” is written in the remarks column.

<HIP processing conditions>
・ Heating temperature: 1100 ° C
・ Heating time: 2 hours ・ Pressure: 100 MPa

In Table 1, each sample No. Among these sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 1 was omitted.

(Sample No. 27)
[1] First, a metal powder having the composition shown in Table 2 was sampled. As in the case of 1, it was produced by the water atomization method.

  [2] Next, the metal powder was granulated by spray drying. The binder used at this time was polyvinyl alcohol, and the amount used was 1 part by mass with respect to 100 parts by mass of the metal powder. Moreover, 50 mass parts solvent (ion-exchange water) was used with respect to 1 mass part of polyvinyl alcohol. This obtained the granulated powder with an average particle diameter of 50 micrometers.

  [3] Next, this granulated powder was compacted under the molding conditions shown below. A press molding machine was used for this molding. Moreover, the shape of the molded body to be produced was a 20 mm square cube shape.

<Molding conditions>
・ Material temperature: 90 ℃
Molding pressure: 600 MPa (6 t / cm ² )

  [4] Next, the obtained molded body was subjected to heat treatment (degreasing treatment) under the following degreasing conditions to obtain a degreased body.

<Degreasing conditions>
・ Degreasing temperature: 450 ° C
・ Degreasing time: 2 hours (holding time at the degreasing temperature)
・ Degreasing atmosphere: Nitrogen atmosphere

  [5] Next, the obtained degreased body was fired under the firing conditions shown below. This obtained the sintered compact.

<Baking conditions>
・ Baking temperature: 1300 ℃
-Firing time: 3 hours (holding time at the firing temperature)
・ Baking atmosphere: Argon atmosphere

(Sample No. 28-37)
Except for changing the composition of the metal powder for powder metallurgy as shown in Table 2, each sample No. In the same manner as in No. 27, a sintered body was obtained. Sample No. The sintered body of 37 was subjected to HIP treatment under the following conditions after firing.

<HIP processing conditions>
・ Heating temperature: 1100 ° C
・ Heating time: 2 hours ・ Pressure: 100 MPa

In Table 2, each sample No. Among these metal powders for powder metallurgy and sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 2 was omitted.

2. 2. Evaluation of Sintered Body (Zr—Nb System) 2.1 Evaluation of Relative Density According to the method of measuring the density of the sintered metal material defined in JIS Z 2501 (2000), the sintered density was measured and the powder used to manufacture each sintered body The relative density of each sintered body was calculated with reference to the true density of the metal powder for metallurgy.
The calculation results are shown in Tables 3 and 4.

2.2 Evaluation of hardness Sample Nos. With respect to the sintered body, the Brinell hardness was measured according to the method of the Brinell hardness test specified in JIS Z 2243 (2008).
The measured hardness was evaluated according to the following evaluation criteria.

<Evaluation criteria for Brinell hardness>
A: Brinell hardness is 302 or less F: Brinell hardness is over 302 The evaluation results are shown in Tables 3 and 4.

2.3 Evaluation of tensile strength, 0.2% proof stress and elongation With respect to the sintered body, tensile strength, 0.2% proof stress and elongation were measured according to the metal material tensile test method defined in JIS Z 2241 (2011).

And about these measured physical-property values, it evaluated in accordance with the following evaluation criteria.
<Evaluation criteria for tensile strength>
A: Tensile strength of the sintered body is 670 MPa or more B: Tensile strength of the sintered body is 650 MPa or more and less than 670 MPa C: Tensile strength of the sintered body is 630 MPa or more and less than 650 MPa D: Sintering The tensile strength of the body is 610 MPa or more and less than 630 MPa E: The tensile strength of the sintered body is 590 MPa or more and less than 610 MPa F: The tensile strength of the sintered body is less than 590 MPa

<Evaluation criteria for 0.2% proof stress>
A: 0.2% yield strength of the sintered body is 305 MPa or more B: 0.2% yield strength of the sintered body is 285 MPa or more and less than 305 MPa C: 0.2% yield strength of the sintered body is 265 MPa or more and less than 285 MPa D: 0.2% yield strength of the sintered body is 245 MPa or more and less than 265 MPa E: 0.2% yield strength of the sintered body is 225 MPa or more and less than 245 MPa F: 0.2% yield strength of the sintered body is Less than 225 MPa

<Evaluation criteria for elongation>
A: Elongation of sintered body is 48% or more B: Elongation of sintered body is 46% or more and less than 48% C: Elongation of sintered body is 44% or more and less than 46% D: Sintered body E: The elongation of the sintered body is 40% or more and less than 42% F: The elongation of the sintered body is less than 40% The above evaluation results are shown in Tables 3 and 4 Show.

2.4 Evaluation of Fatigue Strength Each sample No. shown in Tables 1 and 2 was used. The fatigue strength of the sintered body was measured.

The fatigue strength was measured according to a test method defined in JIS Z 2273 (1978). The applied waveform of the load corresponding to the repetitive stress was a double sine wave, and the minimum maximum stress ratio (minimum stress / maximum stress) was 0.1. The repetition frequency was 30 Hz, and the number of repetitions was 1 × 10 ⁷ times.

And the measured fatigue strength was evaluated according to the following evaluation criteria.
<Fatigue strength evaluation criteria>
A: The fatigue strength of the sintered body is 430 MPa or more B: The fatigue strength of the sintered body is 410 MPa or more and less than 430 MPa C: The fatigue strength of the sintered body is 390 MPa or more and less than 410 MPa D: The fatigue of the sintered body The strength is 370 MPa or more and less than 390 MPa E: The fatigue strength of the sintered body is 350 MPa or more and less than 370 MPa F: The fatigue strength of the sintered body is less than 350 MPa The above evaluation results are shown in Tables 3 and 4.

  As is apparent from Tables 3 and 4, the sintered body corresponding to the example has a higher relative density than the sintered body corresponding to the comparative example (excluding the sintered body subjected to HIP treatment). Was recognized. It was also recognized that there were significant differences in properties such as tensile strength, 0.2% proof stress and elongation.

  On the other hand, when the respective physical property values were compared between the sintered body corresponding to the example and the sintered body subjected to the HIP treatment, it was recognized that both were comparable.

2.5 Sectional Observation of Sintered Body Using Scanning Electron Microscope (SEM) An observation image was obtained with a scanning electron microscope (JXA-8500F, manufactured by JEOL Ltd.) for the cross section of the sintered body corresponding to the example. In addition, the acceleration voltage at the time of imaging was 15 kV, and the magnification was 10,000 times.

  As a result of the observation, in the cross section of each sintered body, a granular region (first region) that exhibits a dark color on the observation image, and a region that displays a light color (second region) that is positioned so as to surround the first region. It was recognized. Therefore, when the average value of the equivalent circle diameters of the first region was obtained, it was about 2 μm or more and 10 μm or less in any sintered body.

  Next, qualitative and quantitative analysis of the observation region was performed using an electron beam microanalyzer. As a result, in the first region, the sum of the Si content and the O content was between 2 and 5 times the Fe content. Further, the Si content in the first region was 10 times or more the Si content in the second region. Further, the Zr content in the first region was three times or more the Zr content in the second region.

  From the above, in the sintered body corresponding to the example, it is recognized that silicon oxide is accumulated with Zr carbide or the like as a nucleus.

  Therefore, according to the present invention, the same high density and excellent machine as the HIP treatment is applied to the sintered body without performing the additional treatment for increasing the density like the HIP treatment. It has become clear that it is possible to impart special characteristics.

  In addition, when the crystal structure analysis by X-ray diffraction was performed about the sintered compact corresponding to an Example, it was recognized that all have the crystal structure of austenitic stainless steel mainly.

3. Production of sintered body (Hf-Nb system) (Sample Nos. 38 to 53)
Except for changing the composition and the like of the metal powder for powder metallurgy as shown in Table 5, each sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1.

In Table 5, each sample No. Among these sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 5 was omitted.

4). 4. Evaluation of Sintered Body (Hf-Nb System) 4.1 Evaluation of Relative Density According to the method of measuring the density of the sintered metal material defined in JIS Z 2501 (2000), the sintered density was measured and the powder used to manufacture each sintered body The relative density of each sintered body was calculated with reference to the true density of the metal powder for metallurgy.
Table 6 shows the calculation results.

4.2 Evaluation of hardness Each sample No. shown in Table 5 With respect to the sintered body, the Brinell hardness was measured according to the method of the Brinell hardness test specified in JIS Z 2243 (2008).

The measured hardness was evaluated according to the evaluation criteria described in 2.2.
The evaluation results are shown in Table 6.

4.3 Evaluation of tensile strength, 0.2% proof stress and elongation Each sample No. shown in Table 5 With respect to the sintered body, tensile strength, 0.2% proof stress and elongation were measured according to the metal material tensile test method defined in JIS Z 2241 (2011).

The measured physical property values were evaluated according to the evaluation criteria described in 2.3.
The evaluation results are shown in Table 6.

  As can be seen from Table 6, the sintered body corresponding to the example was found to have a higher relative density than the sintered body corresponding to the comparative example. It was also recognized that there were significant differences in properties such as tensile strength, 0.2% proof stress and elongation.

5. Production of sintered body (Ti-Nb system) (Sample Nos. 54-66)
Except for changing the composition and the like of the metal powder for powder metallurgy as shown in Table 7, each sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1.

(Sample No. 67)
A metal powder having an average particle diameter of 6.77 μm, a Ti powder having an average particle diameter of 40 μm, and an Nb powder having an average particle diameter of 25 μm were mixed to prepare a mixed powder. In addition, in preparation of mixed powder, each mixing amount of metal powder, Ti powder, and Nb powder was adjusted so that the composition of mixed powder might become a composition shown in Table 11.

  Next, using this mixed powder, sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1.

In Table 7, each sample No. Among these sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 7 was omitted.

6). Evaluation of Sintered Body (Ti-Nb System) 6.1 Evaluation of Relative Density According to the method of measuring the density of the sintered metal material defined in JIS Z 2501 (2000), the sintered density was measured and the powder used to manufacture each sintered body The relative density of each sintered body was calculated with reference to the true density of the metal powder for metallurgy.
Table 8 shows the calculation results.

6.2 Evaluation of Hardness Each sample No. shown in Table 7 With respect to the sintered body, the Brinell hardness was measured according to the method of the Brinell hardness test specified in JIS Z 2243 (2008).

The measured hardness was evaluated according to the evaluation criteria described in 2.2.
The evaluation results are shown in Table 8.

6.3 Evaluation of tensile strength, 0.2% proof stress and elongation Each sample No. shown in Table 7 With respect to the sintered body, tensile strength, 0.2% proof stress and elongation were measured according to the metal material tensile test method defined in JIS Z 2241 (2011).

The measured physical property values were evaluated according to the evaluation criteria described in 2.3.
The evaluation results are shown in Table 8.

  As can be seen from Table 8, the sintered body corresponding to the example was found to have a higher relative density than the sintered body corresponding to the comparative example. It was also recognized that there were significant differences in properties such as tensile strength, 0.2% proof stress and elongation.

7). Production of sintered body (Y-Nb system) (Sample Nos. 68-80)
Except for changing the composition and the like of the metal powder for powder metallurgy as shown in Table 9, sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1.

In Table 9, each sample No. Among these sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 9 was omitted.

8). Evaluation of Sintered Body (Y-Nb System) 8.1 Evaluation of Relative Density Each sample No. shown in Table 9 According to the method of measuring the density of the sintered metal material defined in JIS Z 2501 (2000), the sintered density was measured and the powder used to manufacture each sintered body The relative density of each sintered body was calculated with reference to the true density of the metal powder for metallurgy.
Table 10 shows the calculation results.

8.2 Evaluation of Hardness Each sample No. shown in Table 9 With respect to the sintered body, the Brinell hardness was measured according to the method of the Brinell hardness test specified in JIS Z 2243 (2008).

The measured hardness was evaluated according to the evaluation criteria described in 2.2.
Table 10 shows the evaluation results.

8.3 Evaluation of Tensile Strength, 0.2% Yield Strength and Elongation Each sample No. shown in Table 9 With respect to the sintered body, tensile strength, 0.2% proof stress and elongation were measured according to the metal material tensile test method defined in JIS Z 2241 (2011).

The measured physical property values were evaluated according to the evaluation criteria described in 2.3.
Table 10 shows the evaluation results.

  As is clear from Table 10, the sintered body corresponding to the example was found to have a higher relative density than the sintered body corresponding to the comparative example. It was also recognized that there were significant differences in properties such as tensile strength, 0.2% proof stress and elongation.

9. Production of sintered body (V-Nb system) (Sample Nos. 81-93)
Except for changing the composition of the metal powder for powder metallurgy as shown in Table 11, each sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1.

In Table 11, each sample No. Among these sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 11 was omitted.

10. Evaluation of Sintered Body (V-Nb System) 10.1 Evaluation of Relative Density According to the method of measuring the density of the sintered metal material defined in JIS Z 2501 (2000), the sintered density was measured and the powder used to manufacture each sintered body The relative density of each sintered body was calculated with reference to the true density of the metal powder for metallurgy.
Table 12 shows the calculation results.

10.2 Evaluation of Hardness Each sample No. shown in Table 11 With respect to the sintered body, the Brinell hardness was measured according to the method of the Brinell hardness test specified in JIS Z 2243 (2008).

The measured hardness was evaluated according to the evaluation criteria described in 2.2.
The evaluation results are shown in Table 12.

10.3 Evaluation of tensile strength, 0.2% proof stress and elongation Each sample No. shown in Table 11 With respect to the sintered body, tensile strength, 0.2% proof stress and elongation were measured according to the metal material tensile test method defined in JIS Z 2241 (2011).

The measured physical property values were evaluated according to the evaluation criteria described in 2.3.
The evaluation results are shown in Table 12.

  As apparent from Table 12, the sintered body corresponding to the example was found to have a higher relative density than the sintered body corresponding to the comparative example. It was also recognized that there were significant differences in properties such as tensile strength, 0.2% proof stress and elongation.

11. Production of sintered body (Ti-Zr system) (Sample Nos. 94 to 114)
Except for changing the composition and the like of the metal powder for powder metallurgy as shown in Table 13, Sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1.

In Table 13, each sample No. Among these sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 13 was omitted.

12 Evaluation of Sintered Body (Ti-Zr System) 12.1 Evaluation of Relative Density According to the method of measuring the density of the sintered metal material defined in JIS Z 2501 (2000), the sintered density was measured and the powder used to manufacture each sintered body The relative density of each sintered body was calculated with reference to the true density of the metal powder for metallurgy.
Table 14 shows the calculation results.

12.2 Evaluation of Hardness Each sample No. shown in Table 13 With respect to the sintered body, the Brinell hardness was measured according to the method of the Brinell hardness test specified in JIS Z 2243 (2008).

The measured hardness was evaluated according to the evaluation criteria described in 2.2.
The evaluation results are shown in Table 14.

12.3 Evaluation of tensile strength, 0.2% proof stress and elongation Each sample No. shown in Table 13 With respect to the sintered body, tensile strength, 0.2% proof stress and elongation were measured according to the metal material tensile test method defined in JIS Z 2241 (2011).

The measured physical property values were evaluated according to the evaluation criteria described in 2.3.
The evaluation results are shown in Table 14.

  As is clear from Table 14, the sintered body corresponding to the example was found to have a higher relative density than the sintered body corresponding to the comparative example. It was also recognized that there were significant differences in properties such as tensile strength, 0.2% proof stress and elongation.

13. Production of sintered body (Zr-Ta series) (Sample Nos. 115 to 132)
Except for changing the composition of the metal powder for powder metallurgy as shown in Table 15, each sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1.

In Table 15, each sample No. Among these sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 15 was omitted.

14 Evaluation of sintered body (Zr-Ta system) 14.1 Evaluation of relative density According to the method of measuring the density of the sintered metal material defined in JIS Z 2501 (2000), the sintered density was measured and the powder used to manufacture each sintered body The relative density of each sintered body was calculated with reference to the true density of the metal powder for metallurgy.
Table 16 shows the calculation results.

14.2 Evaluation of Hardness Each sample No. shown in Table 15 With respect to the sintered body, the Brinell hardness was measured according to the method of the Brinell hardness test specified in JIS Z 2243 (2008).

The measured hardness was evaluated according to the evaluation criteria described in 2.2.
The evaluation results are shown in Table 16.

14.3 Evaluation of tensile strength, 0.2% proof stress and elongation Each sample No. shown in Table 15 With respect to the sintered body, tensile strength, 0.2% proof stress and elongation were measured according to the metal material tensile test method defined in JIS Z 2241 (2011).

The measured physical property values were evaluated according to the evaluation criteria described in 2.3.
The evaluation results are shown in Table 16.

  As is clear from Table 16, the sintered body corresponding to the example was found to have a higher relative density than the sintered body corresponding to the comparative example. It was also recognized that there were significant differences in properties such as tensile strength, 0.2% proof stress and elongation.

15. Production of sintered body (Zr-V system) (Sample No. 133-150)
Except for changing the composition and the like of the metal powder for powder metallurgy as shown in Table 17, each sample No. A sintered body was obtained in the same manner as in the method for producing a sintered body of No. 1.

In Table 17, each sample No. Among these sintered bodies, those corresponding to the present invention are referred to as “Examples”, and those not corresponding to the present invention are referred to as “Comparative Examples”.
Each sintered body contained a small amount of impurities, but the description in Table 17 was omitted.

16. Evaluation of sintered body (Zr-V system) 16.1 Evaluation of relative density According to the method of measuring the density of the sintered metal material defined in JIS Z 2501 (2000), the sintered density was measured and the powder used to manufacture each sintered body The relative density of each sintered body was calculated with reference to the true density of the metal powder for metallurgy.
Table 18 shows the calculation results.

16.2 Evaluation of Hardness Each sample No. shown in Table 17 With respect to the sintered body, the Brinell hardness was measured according to the method of the Brinell hardness test specified in JIS Z 2243 (2008).

The measured hardness was evaluated according to the evaluation criteria described in 2.2.
The evaluation results are shown in Table 18.

16.3 Evaluation of Tensile Strength, 0.2% Yield Strength and Elongation Each sample No. shown in Table 17 With respect to the sintered body, tensile strength, 0.2% proof stress and elongation were measured according to the metal material tensile test method defined in JIS Z 2241 (2011).

The measured physical property values were evaluated according to the evaluation criteria described in 2.3.
The evaluation results are shown in Table 18.

  As is clear from Table 18, the sintered body corresponding to the example was found to have a higher relative density than the sintered body corresponding to the comparative example. It was also recognized that there were significant differences in properties such as tensile strength, 0.2% proof stress and elongation.

Claims (14)

Fe is the main component,
Cr is contained in a ratio of 6% by mass to 32% by mass,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is included at a ratio of 0.005 mass% to 1.4 mass%,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
The metal powder for powder metallurgy, wherein the second element is contained in a proportion of 0.01% by mass or more and 2% by mass or less. Fe is the main component,
Cr is contained in a proportion of 16% by mass or more and 27% by mass or less,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained at a ratio of 0.4 mass% to 2.5 mass%,
C is included in a proportion of 0.05% by mass or more and 0.75% by mass or less,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a proportion of 0.03% by mass or more and 0.5% by mass or less,
The metal powder for powder metallurgy, characterized in that the second element is contained at a ratio of 0.03 mass% or more and 0.5 mass% or less. Fe is the main component,
Cr is contained in a proportion of 20% by mass or more and 26% by mass or less,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained in a proportion of 0.75 mass% or more and 1.75 mass% or less,
C is contained in a proportion of 0.3% by mass or more and 0.5% by mass or less,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a proportion of 0.05% by mass or more and 0.2% by mass or less,
The metal powder for powder metallurgy characterized by containing the said 2nd element in the ratio of 0.05 mass% or more and 0.2 mass% or less. Fe is the main component,
Cr is contained in a ratio of 12% by mass to 32% by mass,
Ni is contained in a ratio of 3% by mass to 41% by mass,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is contained in a proportion of 0.005% by mass or more and 0.8% by mass or less,
Nb is contained in a ratio of 0.7% by mass or more and 2% by mass or less,
Ti, V, Y, and one element selected from the group consisting of Zr and Hf as a first element, V, Z r, 1 or element in a by periodic that are selected from the group consisting of Hf and Ta When the element in the table is larger than the first element or the element in the periodic table is the same as the first element and the element in the periodic table is larger than the first element as the second element,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
The metal powder for powder metallurgy, wherein the second element is contained in a proportion of 0.01% by mass or more and 2% by mass or less. The ratio X1 / X2 of the value X1 obtained by dividing the content E1 of the first element by the atomic weight of the first element with respect to the value X2 obtained by dividing the content E2 of the second element by the atomic weight of the second element is 0. The metal powder for powder metallurgy according to any one of claims 1 to 4, which is 3 or more and 3 or less.   The metal powder for powder metallurgy according to any one of claims 1 to 5, wherein the total content of the first element and the content of the second element is 0.05% by mass or more and 0.6% by mass or less. .   The metal powder for powder metallurgy according to any one of claims 1 to 6, which has an austenite crystal structure. The metal powder for powder metallurgy according to any one of claims 1 to 7 , having an average particle size of 0.5 µm to 30 µm. A compound comprising: the metal powder for powder metallurgy according to any one of claims 1 to 8 ; and a binder that binds particles of the metal powder for powder metallurgy. A granulated powder obtained by granulating the metal powder for powder metallurgy according to any one of claims 1 to 8 . Fe is the main component,
Cr is contained in a ratio of 6% by mass to 32% by mass,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is included at a ratio of 0.005 mass% to 1.4 mass%,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
A sintered body produced by sintering metal powder for powder metallurgy containing the second element in a proportion of 0.01% by mass or more and 2% by mass or less. Fe is the main component,
Cr is contained in a ratio of 6% by mass to 32% by mass,
Ni is contained at a ratio of 12% by mass or more and 41% by mass or less,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is included at a ratio of 0.005 mass% to 1.4 mass%,
Ti, V, Y, Zr, and one element selected from the group consisting of Nb and Hf as a first element, V, Z r, Nb, with one kind of element selected from the group consisting of Hf and Ta When the element in the periodic table of elements is larger than the first element or the element in the periodic table of elements is the same as the first element and the element in the periodic table of elements is larger than the first element is the second element. ,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
A sintered body characterized in that the second element is contained in a proportion of 0.01% by mass or more and 2% by mass or less. Fe is the main component,
Cr is contained in a ratio of 12% by mass to 32% by mass,
Ni is contained in a ratio of 3% by mass to 41% by mass,
The Mn content is 2% by mass or less,
Si is contained in a ratio of 0.3% by mass to 3% by mass,
C is contained in a proportion of 0.005% by mass or more and 0.8% by mass or less,
Nb is contained in a ratio of 0.7% by mass or more and 2% by mass or less,
Ti, V, Y, and one element selected from the group consisting of Zr and Hf as a first element, V, Z r, 1 or element in a by periodic that are selected from the group consisting of Hf and Ta When the element in the table is larger than the first element or the element in the periodic table is the same as the first element and the element in the periodic table is larger than the first element as the second element,
The first element is included in a ratio of 0.01% by mass to 2% by mass,
A sintered body characterized in that the second element is contained in a proportion of 0.01% by mass or more and 2% by mass or less. The sintered body according to any one of claims 11 to 13 , comprising a first region and a second region having a silicon oxide content lower than that of the first region.