CN109585151B - Method for producing R-T-B sintered magnet and diffusion source - Google Patents
Method for producing R-T-B sintered magnet and diffusion source Download PDFInfo
- Publication number
- CN109585151B CN109585151B CN201811137401.6A CN201811137401A CN109585151B CN 109585151 B CN109585151 B CN 109585151B CN 201811137401 A CN201811137401 A CN 201811137401A CN 109585151 B CN109585151 B CN 109585151B
- Authority
- CN
- China
- Prior art keywords
- sintered magnet
- alloy
- mass
- magnet material
- diffusion source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
- H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
- H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
Abstract
The subject is as follows: the magnet characteristics of the R-T-B sintered magnet are improved. The solution of the problem lies in: the method for producing an R-T-B sintered magnet of the present invention comprises: preparing a R-T-B sintered magnet material; preparing a Pr-Ga alloy prepared by a molten-state spin-solidification method; a step of obtaining a diffusion source from a powder of the Pr-Ga alloy by heat-treating the Pr-Ga alloy at a temperature of 270 ℃ or higher and not higher than the melting point of the Pr-Ga alloy; and a step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere, thereby diffusing Pr and Ga from the diffusion source into the R-T-B sintered magnet material.
Description
Technical Field
The present invention relates to a method for producing an R-T-B sintered magnet and a diffusion source.
Background
R-T-B sintered magnets (R is at least one of rare earth elements, and nd.t is Fe or Fe and Co, and B is boron) are known as magnets having the highest performance among permanent magnets, and are used in Voice Coil Motors (VCM) for hard disk drives, various engines such as electric automobile (EV, HV, PHV, etc.), industrial equipment engines, and various types of engines, home electric appliances, and the like.
The R-T-B sintered magnet is mainly composed of R2T14The main phase of the B compound and a grain boundary phase located in a grain boundary portion of the main phase. R as the main phase2T14The B compound is a ferromagnetic material having high saturation magnetization and an anisotropic magnetic field, and is the basis of the characteristics of R-T-B sintered magnets.
Coercive force H of R-T-B sintered magnet at high temperaturecJ(hereinafter, it may be simply referred to as "HcJ") is reduced, and thus irreversible thermal demagnetization occurs. Therefore, especially in the electric automobile engineHigh H is required for R-T-B sintered magnets used in machinescJ。
In R-T-B sintered magnets, it is known that R is2T14When a part of the light rare earth element RL (e.g., Nd, Pr) contained in R in the B compound is substituted with the heavy rare earth element RH (e.g., Dy, Tb), HcJAnd (4) improving. H with increasing amount of RH replacementcJAnd (4) improving.
However, R is substituted2T14When RL in B compound is replaced with RH, H of R-T-B sintered magnetcJIncreased, but residual magnetic flux density Br(hereinafter, it may be simply referred to as "B" in some casesr") is decreased. In addition, there are problems such as unstable supply and large price fluctuation, particularly because RH such as Dy is available in a small amount of resources and limited in production places. Therefore, in recent years, it has been desired to use H as little as possible without using RHcJAnd (4) improving.
Patent document 1 discloses an R-T-B based rare earth sintered magnet with a high coercive force while suppressing the Dy content. The composition of the sintered magnet is limited to a specific range in which the amount of B is relatively small compared with that of a generally used R-T-B alloy, and contains 1 or more metal elements M selected from Al, Ga and Cu. As a result, R is formed in the grain boundary2T17From the R of2T17Transition metal rich phase (R) formed at grain boundaries6T13M) is increased, whereby HcJAnd (4) improving.
Documents of the prior art
Patent document
Patent document 1: international publication No. 2013/008756
Disclosure of Invention
Problems to be solved by the invention
In the R-T-B-based rare earth sintered magnet disclosed in patent document 1, Dy content is reduced and high H content is obtainedcJHowever, B is presentrSuch problems are greatly reduced. In recent years, for applications such as engines for electric vehicles, higher H is requiredcJThe R-T-B sintered magnet of (1).
Various aspects of the present inventionEmbodiments provide reduced RH levels and have high BrAnd high HcJThe method for producing the R-T-B sintered magnet of (1).
Means for solving the problems
In an exemplary embodiment, a method for producing an R-T-B sintered magnet according to the present invention includes: a step of preparing an R-T-B sintered magnet material containing R: 27.5 to 35.0 mass% (R is at least one of rare earth elements, and must include Nd), B: 0.80 to 0.99 mass%, Ga: 0-0.8 mass%, M: 0 to 2 mass% (M is at least one of Cu, Al, Nb and Zr), the rest of T (T is Fe or Fe and Co), and inevitable impurities; preparing a Pr-Ga alloy; a step of obtaining a diffusion source by heat-treating the Pr-Ga alloy at a temperature not lower than 270 ℃ and not higher than the melting point of the Pr-Ga alloy and pulverizing the Pr-Ga alloy after the heat treatment; and a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface to the inside of the R-T-B sintered magnet material, wherein the Pr-Ga alloy is an alloy produced by a melt spinning (melt spinning) method.
In another exemplary embodiment, a method for producing an R-T-B sintered magnet according to the present invention includes: a step of preparing an R-T-B sintered magnet material containing R: 27.5 to 35.0 mass% (R is at least one of rare earth elements, and must include Nd), B: 0.80 to 0.99 mass%, Ga: 0-0.8 mass%, M: 0 to 2 mass% (M is at least one of Cu, Al, Nb and Zr), the rest of T (T is Fe or Fe and Co), and inevitable impurities; crushing Pr-Ga alloy to prepare Pr-Ga alloy powder; a step of obtaining a diffusion source from the Pr-Ga alloy powder by heat-treating the Pr-Ga alloy powder at a temperature of 270 ℃ or higher and a melting point or lower than the melting point of the Pr-Ga alloy powder; and a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface to the inside of the R-T-B sintered magnet material, wherein the Pr-Ga alloy is an alloy produced by a melt-spin-solidification method.
In one embodiment, the R-T-B sintered magnet material satisfies the following inequality (1).
[T]/55.85＞14[B]/10.8 (1)
([ T ] is the content of T in mass%, [ B ] is the content of B in mass%)
In one embodiment, the Ga content of the R-T-B sintered magnet material is 0 to 0.5 mass%.
In one embodiment, the Nd content of the Pr — Ga alloy is equal to or less than an inevitable impurity content.
The method for producing an R-T-B sintered magnet of the present invention comprises: a step of preparing an R-T-B sintered magnet material containing R: 27.5 to 35.0 mass% (R is at least one of rare earth elements, and must include Nd), B: 0.80 to 0.99 mass%, Ga: 0-0.8 mass%, M: 0 to 2 mass% (M is at least one of Cu, Al, Nb and Zr), the rest of T (T is Fe or Fe and Co), and inevitable impurities; preparing a Pr-Ga alloy; a step of obtaining a diffusion source by heat-treating the Pr-Ga alloy at a temperature which is 230 ℃ or higher and lower than the melting point of the Pr-Ga alloy and pulverizing the Pr-Ga alloy after the heat treatment; and a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a process chamber, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface to the inside of the R-T-B sintered magnet material, wherein the Pr-Ga alloy is an alloy produced by a strip casting (strip cast) method.
In another exemplary embodiment, a method for producing an R-T-B sintered magnet according to the present invention includes: a step of preparing an R-T-B sintered magnet material containing R: 27.5 to 35.0 mass% (R is at least one of rare earth elements, and must include Nd), B: 0.80 to 0.99 mass%, Ga: 0-0.8 mass%, M: 0 to 2 mass% (M is at least one of Cu, Al, Nb and Zr), the rest of T (T is Fe or Fe and Co), and inevitable impurities; a step for pulverizing a Pr-Ga alloy to prepare Pr-Ga alloy powder; a step of obtaining a diffusion source from the Pr-Ga alloy powder by heat-treating the Pr-Ga alloy powder at a temperature which is 230 ℃ or higher and lower than the melting point of the Pr-Ga alloy powder; and a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source in a vacuum or inert gas atmosphere at a temperature exceeding 600 ℃ and up to 950 ℃, thereby diffusing Pr and Ga contained in the diffusion source from the surface to the interior of the R-T-B sintered magnet material, wherein the Pr-Ga alloy is an alloy produced by a strip casting method.
In one embodiment, the R-T-B sintered magnet material satisfies the following inequality (1).
[T]/55.85＞14[B]/10.8 (1)
([ T ] is the content of T in mass%, [ B ] is the content of B in mass%)
In one embodiment, the Ga content of the R-T-B sintered magnet material is 0 to 0.5 mass%.
In one embodiment, the Nd content of the Pr — Ga alloy is equal to or less than an inevitable impurity content.
The diffusion source of the present invention is a Pr-Ga alloy powder composed of particles of an intermetallic compound having an average crystal grain diameter of more than 3 μm, the particles having a cross-section in a flake shape.
In one embodiment, the Nd content of the Pr — Ga alloy is equal to or less than an inevitable impurity content.
ADVANTAGEOUS EFFECTS OF INVENTION
According to an embodiment of the present invention, Pr and Ga are diffused from particles having a uniform structure of Pr-Ga alloy powder by performing a diffusion step by heat-treating a Pr-Ga alloy produced by a melt-spin-solidification method, disposing the obtained diffusion source and a R-T-B sintered magnet material in a treatment vessel, and performing diffusion. Thereby, high B can be obtainedrAnd HcJ. In addition, it is possible to suppress variations in magnetic characteristics caused by diffusion and to suppress B caused by variations in magnetic characteristicsrAnd HcJIs reduced.
Drawings
Fig. 1A is a cross-sectional view schematically showing a part of an R-T-B-based sintered magnet material prepared in an embodiment of the present invention.
Fig. 1B is a cross-sectional view schematically showing a part of an R-T-B-based sintered magnet raw material in a state of being in contact with a diffusion source in the embodiment of the present invention.
Description of the symbols
30 powder particles constituting a diffusion source
100R-T-B sintered magnet material
Upper surface of 100a R-T-B series sintered magnet raw material
Side surface of 100B R-T-B sintered magnet material
Side surface of 100c R-T-B sintered magnet material
Detailed Description
In the present specification, the rare earth element is at least 1 element selected from scandium (Sc), yttrium (Y), and lanthanoid elements. Here, the lanthanoid element is a generic name of 15 elements from lanthanum to lutetium.
In the present invention, the R-T-B sintered magnet in the diffusion step and the diffusion step is referred to as "R-T-B sintered magnet raw material", and the R-T-B sintered magnet after the diffusion step is simply referred to as "R-T-B sintered magnet".
An exemplary embodiment of a method for producing an R-T-B sintered magnet according to the present invention includes:
1. a step for preparing a R-T-B sintered magnet raw material (R is at least one of rare earth elements and essentially contains Nd);
2. preparing a Pr-Ga alloy;
3. a step of obtaining a diffusion source by heat-treating the Pr-Ga alloy at a temperature not lower than 270 ℃ and not higher than the melting point of the Pr-Ga alloy and pulverizing the Pr-Ga alloy after the heat treatment; and
4. and a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface into the interior of the R-T-B sintered magnet material.
In this embodiment, the Pr — Ga alloy is an alloy produced by a melt-spin-solidification method.
Still another exemplary embodiment of the R-T-B sintered magnet according to the present invention includes:
a step of preparing an R-T-B sintered magnet raw material (R is at least one of rare earth elements and must contain Nd);
a step of pulverizing a Pr-Ga alloy to prepare a Pr-Ga alloy powder;
a step of obtaining a diffusion source from the Pr-Ga alloy powder by heat-treating the Pr-Ga alloy powder at a temperature of 270 ℃ or higher and not higher than the melting point of the Pr-Ga alloy powder; and
and a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface into the interior of the R-T-B sintered magnet material.
In this embodiment, the alloy is an alloy produced by a melt-spinning method.
Still another exemplary embodiment of the method for producing an R-T-B sintered magnet according to the present invention includes:
1. a step for preparing a R-T-B sintered magnet raw material (R is at least one of rare earth elements and essentially contains Nd);
2. preparing a Pr-Ga alloy;
3. a step of obtaining a diffusion source by heat-treating the Pr-Ga alloy at a temperature which is 230 ℃ or higher and lower than the melting point of the Pr-Ga alloy and pulverizing the Pr-Ga alloy after the heat treatment; and
4. and a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface into the interior of the R-T-B sintered magnet material.
In this embodiment, the Pr — Ga alloy is an alloy produced by a strip casting method.
Still another exemplary embodiment of the R-T-B sintered magnet according to the present invention includes:
a step of preparing an R-T-B sintered magnet raw material (R is at least one of rare earth elements and must contain Nd);
a step of pulverizing a Pr-Ga alloy to prepare a Pr-Ga alloy powder;
a step of obtaining a diffusion source from the Pr-Ga alloy powder by heat-treating the Pr-Ga alloy powder at a temperature which is 230 ℃ or higher and lower than the melting point of the Pr-Ga alloy powder; and
and a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface into the interior of the R-T-B sintered magnet material.
In the present embodiment, the alloy is an alloy produced by a strip casting method.
As described above, the powder of the alloy constituting the diffusion source by the heat treatment is composed of particles having an average crystal grain diameter exceeding 3 μm. Thus, the preferable range of the heat treatment differs depending on the alloy obtained by the melt-spinning method and the strip casting method. In addition, in order to obtain a diffusion source composed of particles of the intermetallic compound having an average crystal grain diameter of more than 3 μm, a method other than the above-described heat treatment may be used. For example, the intermetallic compound particles having an average crystal grain size of more than 3 μm can be obtained by adjusting the cooling conditions, holding temperature and holding time of the alloy obtained by the melt-spinning method and/or the strip casting method.
In the present invention, the above alloy is an alloy produced by a melt-spinning method or a strip casting method. The diffusion source may be manufactured from a powder of the alloy. In an exemplary embodiment of a diffusion source according to the present invention,
(1) is powder of Pr-Ga alloy;
(2) the powder of the Pr-Ga alloy is composed of particles of an intermetallic compound having an average crystal grain diameter of more than 3 [ mu ] m;
(3) the cross section of the particles is in the shape of flakes.
The diffusion source is composed of particles of an intermetallic compound having an average crystal grain diameter of more than 3 μm, and therefore, H in the R-T-B sintered magnet can be improved while suppressing variations in characteristicscJ。
In the present invention, the diffusion source is a powder of an alloy obtained by pulverizing an alloy obtained by a melt-spinning method and/or a strip casting method. Therefore, the cross section of the particles of the powder constituting the diffusion source is in the shape of flakes.
The differences between the above 1 to 4 and the above 1 'to 4' are only in the case where the diffusion source is obtained by heat-treating a Pr-Ga alloy and pulverizing the Pr-Ga alloy after the heat treatment (the above 1 to 4) and the case where the diffusion source is obtained by heat-treating a powder of the Pr-Ga alloy obtained by pulverizing the Pr-Ga alloy (the above 1 'to 4'). Therefore, the descriptions 1 to 4 are omitted, and the descriptions of the above l 'to 4' are omitted.
Hereinafter, embodiments of the present invention will be described. In addition, detailed description of unnecessary portions may be omitted. For example, detailed descriptions of known matters and repetitive descriptions of substantially the same configuration may be omitted. This is to avoid the following description from unnecessarily becoming redundant and readily understandable to those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the invention. And are not intended to limit the scope of the claimed subject matter.
1. Process for preparing R-T-B sintered magnet material
An R-T-B sintered magnet material (R is at least one of rare earth elements and must contain Nd) to be subjected to Pr and Ga diffusion is prepared.
The R-T-B sintered magnet material contains:
r: 27.5 to 35.0 mass% (R is at least one of rare earth elements, and must contain Nd),
B: 0.80 to 0.99% by mass,
ga: 0 to 0.8% by mass,
m: 0 to 2 mass% (M is at least one of Cu, Al, Nb and Zr),
The rest of T (T is Fe or Fe and Co) and inevitable impurities.
(R)
The content of R is 27.5 to 35.0 mass%. When R is less than 27.5 mass%, a liquid phase is not sufficiently generated during sintering, and it becomes difficult to sufficiently densify the sintered body. On the other hand, the effect of the present invention can be obtained even if R exceeds 35.0 mass%, but since the alloy powder becomes very active in the sintered body production process and there is a possibility that significant oxidation, ignition, and the like of the alloy powder occur, it is preferably 35 mass% or less. R is more preferably 28 to 33% by mass, and still more preferably 29 to 33% by mass. The content of RH is preferably 5 mass% or less of the entire R-T-B sintered magnet material. The present invention can obtain high B content without using RHrAnd high HcJTherefore, higher H is requiredcJCan also reduceThe amount of added RH.
(B)
The content of B is 0.80-0.99 mass%. A high B content can be obtained by diffusing the Pr-Ga alloy described later into an R-T-B sintered magnet material having a B content of 0.80 to 0.99 mass%rAnd high HcJ. When the content of B is less than 0.80% by mass, B is present in an amount such thatrA possibility of reduction, when it exceeds 0.99% by mass, H may be caused to existcJThe likelihood of reduction. In addition, a part of B can be replaced with C.
(Ga)
The content of Ga in the R-T-B sintered magnet material before Ga diffusion is 0-0.8 mass% from the Pr-Ga alloy powder. In the present invention, Ga is introduced by diffusing powder of Pr-Ga alloy into the R-T-B sintered magnet material, and therefore the Ga content of the R-T-B sintered magnet material is set to be relatively small (or not). When the content of Ga exceeds 0.8 mass%, the main phase contains Ga, so that the magnetization of the main phase is lowered and high B cannot be obtainedrThe possibility of (a). The Ga content is preferably 0.5 mass% or less. Higher B can be obtainedr。
(M)
The content of M is 0 to 2 mass%. M is at least one of Cu, Al, Nb, and Zr, and the effect of the present invention can be achieved even if it is 0 mass%, and 2 mass% or less can be contained in the total of Cu, Al, Nb, and Zr. By containing Cu and Al, H can be increasedcJ. Cu and Al may be added actively, or elements inevitably introduced in the production process using the raw material or alloy powder may be used. Further, by containing Nb and Zr, abnormal grain growth of crystal grains during sintering can be suppressed. Preferably, M is essentially Cu, and 0.05 to 0.30 mass% of Cu is contained. By containing 0.05 to 0.30 mass% of Cu, H can be further increasedcJ。
(remainder T)
The balance being T (T being Fe or Fe and Co) and impurities. In one embodiment, T satisfies inequality (1). Preferably, at least 90% of T is Fe by mass ratio. A part of Fe can be replaced with Co. However, when the amount of Co substitution exceeds 10% by mass of the total T,Brit is not preferable because it is low. The R-T-B sintered magnet material of the present invention may contain impurities that are usually inevitable in alloys such as didymium (Nd-Pr), electrolytic iron, and ferroboron and are usually contained in the production process, and a small amount of elements other than those described above (elements other than R, B, Ga, M, and T). For example, Ti, V, Cr, Mn, Ni, Si, La, Ce, Sm, Ca, Mg, O (oxygen), N (nitrogen), C (carbon), Mo, Hf, Ta, W, etc. may be contained.
The R-T-B sintered magnet material of the present invention preferably satisfies inequality (1).
[ T ]/55.85 > 14[ B ]/10.8 (inequality (1))
By satisfying the inequality (1), the content of B becomes smaller than that of a general R-T-B sintered magnet. In a general R-T-B sintered magnet, R is formed as a main phase excluding R2T14Fe phase and R are not formed except B phase2T17Of phase [ T]/55.85 (atomic weight of Fe) less than 14[ B]Composition ([ T ] of 10.8 (atomic weight of B))]The content of T in mass% [ B ]]The content of B in mass%). In a preferred embodiment of the present invention, the R-T-B sintered magnet material is different from a general R-T-B sintered magnet in [ T ]]/55.85 (atomic weight of Fe) greater than 14[ B]The mode of/10.8 (atomic weight of B) is defined by inequality (1). In the R-T-B sintered magnet material of the present invention, T is Fe as a main component, and therefore the atomic weight of Fe is used.
2. Process for preparing Pr-Ga alloy
[ Pr-Ga alloy ]
Pr of the Pr-Ga alloy accounts for 65-97 mass% of the total Pr-Ga alloy. 30% by mass or less of Pr can be substituted with Nd, and 20% by mass or less of Pr can be substituted with Dy and/or Tb. Ga accounts for 3 to 35 mass percent of the total Pr-Ga alloy, and less than 50 mass percent of Ga can be replaced by Cu. The Pr — Ga alloy may contain inevitable impurities. In the present invention, "30% or less of Pr can be substituted with Nd" means that 30% of Pr can be substituted with Nd, assuming that the content (mass%) of Pr in the Pr — Ga alloy is 100%. For example, if Pr in a Pr — Ga alloy is 70 mass% (Ga is 30 mass%), Nd can be substituted to 21 mass%. That is, Pr was 49 mass%, and Nd was 21 mass%. The same applies to Dy, Tb and Cu.
By subjecting the R-T-B sintered magnet material having the composition range of the present invention to the later-described diffusion step using a powder of Pr-Ga alloy in which Pr and Ga are in the above ranges, Ga can be diffused to the deep inside of the magnet through the grain boundaries. Pr can be substituted with Nd, Dy and/or Tb, but if the substitution amounts of each are outside the above ranges, Pr is too small, and thus high B cannot be obtainedrAnd high HcJ. The Nd content of the Pr — Ga alloy is preferably equal to or less than an unavoidable impurity content (approximately 1 mass% or less). Ga can be substituted by Cu at 50% or less, but if the amount of Cu substitution exceeds 50%, H is presentcJThe likelihood of reduction.
In the present invention, the Pr-Ga alloy is produced by a melt-spinning method or a strip casting method.
In the melt-spinning method, a molten alloy is sprayed onto the surface of a metal chill roll rotating at a high speed, and the molten alloy is brought into contact with the surface of the chill roll and rapidly solidified. In order to bring an appropriate amount of the alloy melt into contact with the surface of the cooling roll, the alloy melt is sprayed through a spout (orifice) having an inner diameter reduced to, for example, about 1 mm. The alloy formed is amorphous or microcrystalline. The alloy formed is a ribbon or a scale-like ribbon, and has a thickness of the order of 10 μm (less than 100 μm). However, in the present invention, as described later, the alloy is heat-treated to crystallize in an amorphous state and coarsen crystallites, and finally has a structure suitable as a diffusion source.
The strip casting method is a method of continuously casting a thin-plate alloy by flowing a molten metal on a rotating roll and solidifying the molten metal into a thin-plate by quenching. The alloy formed is in the form of a thin plate having a thickness of the order of 100 μm (e.g., about 100 μm to 500 μm). In the present invention, as described later, the alloy is heat-treated to coarsen crystals and finally has a microstructure suitable as a diffusion source.
When a molten solution of a Pr-Ga alloy is rapidly condensed by a melt-spinning method or a strip casting method, it is difficult to strictly control the cooling rate. Thus, with respect to PThe structure of powder particles constituting the powder of the Pr-Ga alloy after the pulverization of the r-Ga alloy is likely to vary from powder particle to powder particle. Specifically, the particles are formed into an amorphous state or into fine crystals having an average crystal grain size of 1 μm or less. When such variations occur in the structure of the structure and the average crystal grain size, variations occur in the melting temperature of the phase constituting the particles and the rate of supplying Pr and Ga as diffusion sources in the diffusion step described later. Such variations ultimately lead to variations in magnet characteristics. As a result, B may not be highrAnd high HcJThe R-T-B sintered magnet of (1).
In order to solve such a problem, in an embodiment of the present invention, the heat treatment described below is performed.
3. Process for obtaining diffusion source
[ Heat treatment of Pr-Ga alloy ]
In an embodiment of the present invention, a Pr — Ga alloy obtained by a melt-spin-solidification method is heat-treated at a temperature of 270 ℃ or more and not more than the melting point of the Pr — Ga alloy. On the other hand, the alloy obtained by the strip casting method is heat-treated at a temperature not lower than the melting point of the alloy by 230 ℃ and not higher than the melting point.
Thereby, the crystallinity of the powder particles constituting the powder of the Pr-Ga alloy is modified. Further, by pulverizing the Pr — Ga alloy (Pr — Ga alloy after heat treatment), a diffusion source having excellent uniformity can be obtained, and by using the diffusion source, variation in magnetic properties in the diffusion step can be suppressed. The Pr — Ga alloy may be pulverized by a known pulverization method such as pin mill pulverization, and the size of the pulverized powder particles may be 300 μm or less (preferably 200 μm or less). The heat treatment time may be, for example, 30 minutes to 10 hours. The average crystal grain size of the intermetallic compound phase of such a diffusion source exceeds 3 μm. The average crystal grain size of the intermetallic compound phase in the diffusion source is preferably 3.5 μm or more and 20 μm or less. Here, the intermetallic compound phase refers to the entire crystal grains of the intermetallic compound in the powder grains constituting the diffusion source. When there are a plurality of intermetallic compounds in the powder particles constituting the diffusion source, the intermetallic compound is present in the entire crystal grains of the intermetallic compound in the largest amount.
When the heat treatment temperature for the powder of Pr — Ga alloy is lower than 270 ℃ lower than the melting point of the powder of Pr — Ga alloy, the temperature is too low, and therefore, there is a possibility that the crystallinity of the powder particles constituting the powder of alloy cannot be improved, and when the temperature exceeds the melting point, the powders fuse with each other and the diffusion step cannot be efficiently performed.
The heat treatment is preferably performed by adjusting the atmosphere in the furnace so that the oxygen content in the diffusion source after the heat treatment is 0.5 mass% or more and 4.0 mass% or less. By intentionally oxidizing the entire surface of the Pr — Ga alloy, variations in characteristics of each particle due to differences in contact time between the powder particles and the atmosphere, humidity, and the like can be reduced, and variations in magnetic characteristics in the diffusion step can be further reduced. In addition, the possibility of ignition due to contact with oxygen in the atmosphere can be reduced. Therefore, quality control of the diffusion source becomes easy.
In an embodiment, the diffusion source is in the form of a powder. The particle size of the diffusion source in the powder state can be adjusted by sieving. Further, when the powder to be removed by sieving is 10% by mass or less, the influence is small, and therefore, it may be used without sieving.
4. Diffusion process
The R-T-B sintered magnet material and the diffusion source are placed in a processing vessel, and Pr and Ga contained in the diffusion source are diffused from the surface to the inside of the R-T-B sintered magnet material by heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere. Thus, a liquid phase containing Pr and Ga is generated from the diffusion source, and the liquid phase is introduced from the surface of the sintered material into the interior thereof by diffusion through the grain boundary in the R-T-B sintered magnet material. Thus, Ga can diffuse into the depth of the R-T-B sintered magnet material through the grain boundary together with Pr. When the heat treatment temperature is 600 ℃ or lower, there is a case where the amount of the liquid phase containing Pr and Ga is too small to obtain high HcJPossibility of (2)Above 950 ℃ in the presence of HcJThe likelihood of reduction. It is also preferable that the R-T-B sintered magnet subjected to the diffusion step (exceeding 600 ℃ and up to 950 ℃) be cooled from the temperature at which the diffusion step is performed to 300 ℃ at a cooling rate of 5 ℃/min or more. Higher H can be obtainedcJ. More preferably, the cooling rate up to 300 ℃ is 15 ℃/min or more.
In the diffusion step, first, the R-T-B sintered magnet material and the diffusion source are disposed in the processing container. In this case, the R-T-B sintered magnet raw material and the diffusion source are preferably contacted in the processing container. For example, the diffusion step can be performed by covering the surface of the R-T-B sintered magnet material with a diffusion source (powder layer). For example, the diffusion source may be dispersed in a dispersion medium to obtain a slurry, the slurry may be applied to the surface of the R-T-B sintered magnet material, and the dispersion medium may be evaporated to bring the diffusion source into contact with the R-T-B sintered magnet material. Examples of the dispersion medium include alcohols (e.g., ethanol), aldehydes, and ketones. In addition, for example, there can be mentioned: a method of attaching a powdery diffusion source to the R-T-B sintered magnet raw material coated with the binder by using a flow-dipping method; and a method of spraying a powdery diffusion source on the R-T-B sintered magnet material. Further, the treatment container containing the diffusion source may be vibrated, shaken, or rotated, or the powder of the diffusion source may be made to flow in the treatment container.
Fig. 1A is a cross-sectional view schematically showing a part of an R-T-B-based sintered magnet material 100 that can be used in the method for producing an R-T-B-based sintered magnet according to the present invention. In the figure, the upper surface 100a and side surfaces 100B and 100c of the R-T-B sintered magnet material 100 are shown. The shape and size of the R-T-B sintered magnet material used in the production method of the present invention are not limited to the shape and size of the R-T-B sintered magnet material 100 shown in the figure. The upper surface 100a and the side surfaces 100B and 100c of the illustrated R-T-B sintered magnet material 100 are flat, but the surface of the R-T-B sintered magnet material 100 may have irregularities or level differences, or may be curved.
Fig. 1B is a cross-sectional view schematically showing a part of the R-T-B-based sintered magnet raw material 100 in a state where the powder particles 30 constituting the diffusion source are located on the surface. The powder particles 30 constituting the diffusion source located on the surface of the R-T-B based sintered magnet material 100 may be attached to the surface of the R-T-B based sintered magnet material 100 via an unillustrated adhesive layer. Such an adhesive layer can be formed by, for example, applying a coating on the surface of the R-T-B sintered magnet material 100. By using the adhesive layer, the diffusion source powder can be easily attached to a plurality of regions (for example, the upper surface 100a and the side surface 100B) having different normal directions by one coating step without changing the orientation of the R-T-B sintered magnet material 100.
Examples of the binder that can be used include PVA (polyvinyl alcohol), PVB (polyvinyl butyral), PVP (polyvinyl pyrrolidone), and the like. When the binder is an aqueous binder, the R1-T-B sintered magnet may be preheated before application. The purpose of the preliminary heating is to remove excess solvent, control the adhesive force, and make the adhesive adhere uniformly. The heating temperature is preferably 60 to 100 ℃. In the case of an organic solvent-based adhesive having high volatility, this step can be omitted.
The method of applying the binder to the surface of the R-T-B sintered magnet material may be any method. Specific examples of the coating include a spray coating method, a dipping method, and coating with a dispenser.
In a preferred embodiment, a binder is applied to the entire surface (entire surface) of the R-T-B sintered magnet material. Instead of being attached to the entire surface of the R-T-B sintered magnet material, a part of the R-T-B sintered magnet material may be attached. In particular, when the thickness of the R-T-B sintered magnet material is small (e.g., about 2 mm), Pr and Ga may be diffused into the entire magnet by attaching the powder of the diffusion source only to the one surface having the largest area among the surfaces of the R-T-B sintered magnet material, and H may be increasedcJ。
The powder particles constituting the diffusion source that are in contact with the surface of the R-T-B-based sintered magnet material 100 have a structure with excellent uniformity, as described above. Therefore, when heating for diffusion described later is performed, Pr and Ga contained in the diffusion source can be efficiently diffused from the surface of the R-T-B sintered magnet material into the interior without waste.
The amount of Ga applied to the surface of the magnet from the diffusion source may be, for example, in the range of 0.1 to 1.0 mass% (preferably 0.1 to 0.5 mass%) relative to 100 mass% of the R-T-B sintered magnet.
Further, the amounts of Pr and Ga contained in the diffusion source depend not only on the concentrations of Pr and Ga of the powder particles but also on the particle sizes of the powder particles constituting the diffusion source. Therefore, the amounts of Pr and Ga diffused by adjusting the particle size of the powder particles constituting the diffusion source by making the concentrations of Pr and Ga constant can also be adjusted. After the diffusion step, the heating treatment may be further performed at 400 to 800 ℃ for 10 minutes to 72 hours, if necessary.
The Pr — Ga alloy powder obtained by the melt-spin-solidification method is pulverized by a known method such as pin mill pulverization to prepare a Pr — Ga alloy powder, and the Pr — Ga alloy powder is heat-treated at a temperature of 270 ℃ or more and not more than the melting point of the Pr — Ga alloy powder, in the 1 'to 4', except that the description of 1 'to 4' is omitted as described above, the Pr — Ga alloy powder may be produced by the same method as that of 1 to 4.
Examples
Experimental example 1
[ preparation of R-T-B sintered magnet raw Material ]
The raw materials of the respective elements were weighed so that the R-T-B system sintered magnet raw materials had compositions shown in Nos. A-1 and A-2 of Table 1, and alloys were produced by a strip casting method. The obtained alloys were coarsely pulverized by a hydrogen pulverization method to obtain coarsely pulverized powders. Subsequently, 0.04 mass% of zinc stearate as a lubricant was added and mixed to 100 mass% of the obtained coarse pulverized powder, and the mixture was dry-pulverized in a nitrogen stream using a jet mill (jet mill) to obtain a pulverized particle diameter D50Was 4 μm in fine powder (raw alloy powder). In the finely pulverized powder, 0.05 mass% of zinc stearate as a lubricant was added and mixed to 100 mass% of the finely pulverized powder, and then the mixture was molded in a magnetic field to obtain a molded article. The molding device uses a so-called perpendicular magnetic field molding device (transverse magnetic field molding device) in which the magnetic field application direction is orthogonal to the pressing direction. Will be provided withThe obtained molded body was sintered at 1060 ℃ to 1090 ℃ in vacuum (for each sample, a temperature at which densification sufficiently occurred by sintering was selected) for 4 hours to obtain an R-T-B-based sintered magnet material. The density of the R-T-B sintered magnet material obtained was 7.5Mg/m3The above. The results of the composition of the obtained R-T-B sintered magnet material are shown in Table 1. Further, each component in table 1 was measured using high frequency inductively coupled plasma emission spectroscopy (ICP-OES). The same applies to tables 2 and 4 below. In addition, a case where inequality (1) of the present invention is satisfied is denoted by "o", and a case where it is not satisfied is denoted by "x". The total of the compositions in table 1 is not 100% by mass. This is because components other than those listed in table 1 (for example, O (oxygen), N (nitrogen), and the like) are present.
[ Table 1]
[ Process for obtaining a diffusion Source ]
No. a-1 Pr-Ga alloys shown in Table 2 were prepared by the melt spin solidification method. Specifically, in a chamber having an argon atmosphere of 80kPa, a raw material was dissolved by high frequency in a quartz nozzle having a nozzle diameter of 0.8mm, and then a melt was sprayed onto a Cu roll by applying a back pressure of 100 kPa. According to the composition, the Cu roll peripheral speed is within a range of 10 to 40 m/s. Next, the Pr-Ga alloy was heat-treated at 500 ℃ for 2 hours (a temperature 80 ℃ lower than 580 ℃ which is the melting point of the Pr-Ga alloy of No. a-1), and the heat-treated Pr-Ga alloy was pulverized by a pin mill to obtain a diffusion source. The particle size of the diffusion source (alloy powder) was 200 μm or less (confirmed by a sieve).
[ Table 2]
[ diffusion Process ]
The R-T-B sintered magnet materials No. A-1 and A-2 in Table 1 were cut and ground to obtain a cube of 7.4 mm. times.7.4 mm. Then, in the R-T-B sintered magnet material of No. A-1, 3 parts by mass of the diffusion source (1.5 parts by mass per one surface) was dispersed on 100 parts by mass of the R-T-B sintered magnet material on the surfaces (two surfaces) perpendicular to the orientation direction. Thereafter, the diffusion step of heating at 900 ℃ for 4 hours was performed in a reduced pressure argon gas controlled at 50 Pa. Next, the R-T-B sintered magnet and No. A-2 (R-T-B sintered magnet material not subjected to the diffusion step) after the diffusion step were subjected to a second heat treatment at 500 ℃ for 3 hours in a reduced pressure argon atmosphere controlled to 50Pa to produce R-T-B sintered magnets (Nos. 1 and 2). In order to remove the Pr-Ga alloy concentrated portion, No.1 of the R-T-B sintered magnet thus obtained was cut into a size of 0.2mm over the entire surface of each sample by using a surface grinding disk, to obtain a cubic sample of 7.0 mm. times.7.0 mm. The same cutting process was carried out on No.2 of the R-T-B sintered magnet to obtain a cubic sample of 7.0 mm. times.7.0 mm. The composition of the obtained No. 1R-T-B sintered magnet (sample in which Pr and Ga were diffused by using a diffusion source) was measured by high-frequency inductively coupled plasma emission spectrometry (ICP-OES), and the composition was equivalent to that of No.2(No.2 had the same composition as that of No. A-2 since no diffusion source was used).
[ sample evaluation ]
Measuring B with B-H meter for the obtained samplerAnd HcJ. The measurement results are shown in table 3.
[ Table 3]
As described above, although Nos. 1 and 2 are substantially the same composition, as shown in Table 3, the embodiment of the present invention (No.1) attains a high BrAnd high HcJ。
Experimental example 2
In the same manner as in experimental example 1, Nd: 24.0%, Pr: 7.0%, B: 0.86%, Cu: 0.1%, Al: 0.1%, Ga: 0.2%, Co: 0.8%, Fe: 67.0% of R-T-B based sintered magnet raw material (satisfying inequality (1)). The dimensions of the R-T-B sintered magnet material were 5.0mm in thickness, 7.5mm in width and 35mm in length.
Subsequently, in the same manner as in experimental example 1, Pr — Ga alloys having the compositions shown in table 4 were prepared by the melt-spin-solidification method. Next, the Pr-Ga alloy was heat-treated under the conditions (temperature and time) shown in Table 4 (No.3 was not heat-treated), and the heat-treated Pr-Ga alloy was pulverized by a pin mill to obtain a diffusion source (Nos. 3 to 16). The particle size of the diffusion source (alloy powder) was 200 μm or less (confirmed by a sieve). The average crystal grain size of the intermetallic compound phase in the obtained diffusion source was measured by the following method. First, a cross section of the powder particles constituting the diffusion source was observed with a Scanning Electron Microscope (SEM), each phase was identified from the contrast, and the composition of each phase was analyzed using energy dispersive X-ray spectroscopy (EDX) to determine the intermetallic compound phase. Next, the intermetallic compound phase having the highest area ratio was set as the intermetallic compound phase having the highest content by using image analysis software (Scandium), and the crystal grain size of the intermetallic compound phase was determined. Specifically, the number of crystal grains and the total area of crystal grains in the intermetallic compound phase are obtained by using image analysis software (Scandium), and the average area is obtained by dividing the obtained total area of crystal grains by the number of crystal grains. Next, the crystal grain diameter D is determined from the obtained average area by mathematical formula 1.
[ mathematical formula 1]
Wherein D is a crystal grain diameter and S is an average area.
These operations were performed 5 times (5 powder particles were investigated), and the average value was obtained to obtain the average crystal grain size of the intermetallic compound phase in the diffusion source. The results are shown in the average crystal grain size in table 4. In addition, since No.3 did not heat treat the diffusion source, the crystal grain size of the intermetallic compound phase was too small (fine crystal grains of 1 μm or less), and it was not measured.
Next, a binder is applied to the R-T-B sintered magnet material. The coating method comprises the following steps: the R-T-B sintered magnet material was heated on a hot plate to 60 ℃ and then the entire surface of the R-T-B sintered magnet material was coated with a binder by a spray coating method. PVP (polyvinylpyrrolidone) was used as a binder.
Next, the diffusion sources No.3 to 16 in Table 4 were attached to the R-T-B sintered magnet material coated with the binder. 50R-T-B sintered magnet materials to which diffusion sources were attached were prepared for each diffusion source type (Nos. 3 to 16). The adhering method comprises the following steps: a diffusion source (alloy powder) is spread in a container, the temperature of the R-T-B sintered magnet material coated with a binder is reduced to normal temperature, and then the diffusion source is attached to the entire surface of the R-T-B sintered magnet material in the container so as to fill the diffusion source.
Next, the R-T-B sintered magnet material and the diffusion source were placed in a processing vessel, and heated at 900 ℃ for 8 hours to perform a diffusion step of diffusing Pr and Ga contained in the diffusion source from the surface to the inside of the R-T-B sintered magnet material. A cube having a thickness of 4.5mm, a width of 7.0mm and a length of 7.0mm was cut out from the central portion of the R-T-B sintered magnet after diffusion, the coercive force was measured by a B-H meter for 10 of each diffusion source type (Nos. 3 to 16), and the value obtained by subtracting the minimum coercive force value from the maximum coercive force value obtained was used as the magnetic property deviation (. DELTA.H)cJ) And (4) obtaining. Will be Δ HcJThe values of (A) are shown in Table 4.
[ Table 4]
As shown in Table 4, the DeltaH values of the inventive examples (Nos. 4 to 8, 10 to 16) were compared with those of No.3 (comparative example) in which the powder of Pr-Ga alloy was not heat-treated and No.9 (comparative example) in which the heat treatment temperature was out of the range of the present inventioncJBoth are about half, and variations in magnetic properties in the diffusion step are suppressed.
(Experimental example 3)
An experimental example was performed in the same manner as in experimental example 1, except that the alloy was produced by the strip casting method instead of the melt-spinning method. The results are shown in the following table.
[ Table 5]
As shown in Table 5, in comparison with No.17 (comparative example) in which the powders of Pr-Ga alloy were not heat-treated and No.23 (comparative example) in which the heat treatment temperature was out of the range of the present invention, the inventive examples (Nos. 18 to 22 and 24 to 29) had Δ HcJBoth are about half, and variations in magnetic properties in the diffusion step are suppressed.
(Experimental example 4)
The Nd content in the Pr — Ga alloy used in each of the above experimental examples was 5 mass% or 9.5 mass%. In this experimental example, a Pr — Ga alloy having an Nd content of not more than an inevitable impurity content was mainly used. In addition, an experiment was performed in the same manner as in experimental example 1. The results are shown in table 6 below.
[ Table 6]
As shown in Table 5, the DeltaH values of the inventive examples (Nos. 31 to 35, 37 to 48) were compared with those of No.30 (comparative example) in which the powder of the Pr-Ga alloy was not heat-treated and No.36 (comparative example) in which the heat treatment temperature was outside the range of the present inventioncJBoth are about half, and variations in magnetic properties in the diffusion step are suppressed.
Industrial applicability of the invention
According to the present invention, an R-T-B sintered magnet having a high residual magnetic flux density and a high coercive force can be produced. The sintered magnet of the present invention is suitable for various engines such as a hybrid vehicle-mounted engine exposed to high temperatures, home electric appliances, and the like.
Claims (10)
1. A method for producing an R-T-B sintered magnet, comprising:
a step of preparing an R-T-B sintered magnet material, wherein the R-T-B sintered magnet material contains:
r: 27.5 to 35.0 mass%, wherein R is at least one of rare earth elements and essentially contains Nd,
b: 0.80 to 0.99% by mass,
ga: 0 to 0.8% by mass,
m: 0 to 2 mass%, wherein M is at least one of Cu, Al, Nb and Zr,
the balance of T and inevitable impurities, wherein T is Fe or Fe and Co;
preparing a Pr-Ga alloy;
a step of subjecting the Pr-Ga alloy to a heat treatment at a temperature of 270 ℃ or higher and not higher than the melting point of the Pr-Ga alloy for 30 minutes or longer and 10 hours or shorter, and pulverizing the Pr-Ga alloy after the heat treatment, thereby obtaining a diffusion source composed of particles of an intermetallic compound having an average crystal grain size of more than 3 μm; and
a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface to the inside of the R-T-B sintered magnet material,
the Pr-Ga alloy is an alloy prepared by a molten state spin-solidification method.
2. A method for producing an R-T-B sintered magnet, comprising:
a step of preparing an R-T-B sintered magnet material, wherein the R-T-B sintered magnet material contains:
r: 27.5 to 35.0 mass%, wherein R is at least one of rare earth elements and essentially contains Nd,
b: 0.80 to 0.99% by mass,
ga: 0 to 0.8% by mass,
m: 0 to 2 mass%, wherein M is at least one of Cu, Al, Nb and Zr,
the balance of T and inevitable impurities, wherein T is Fe or Fe and Co;
a step for pulverizing a Pr-Ga alloy to prepare Pr-Ga alloy powder;
a step of subjecting the Pr-Ga alloy powder to a heat treatment at a temperature of 270 ℃ or higher and not higher than the melting point of the Pr-Ga alloy powder for 30 minutes or more and 10 hours or less to obtain a diffusion source composed of particles of an intermetallic compound having an average crystal particle diameter of more than 3 μm from the Pr-Ga alloy powder; and
a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface to the inside of the R-T-B sintered magnet material,
the Pr-Ga alloy is an alloy prepared by a molten state spin-solidification method.
3. The method of manufacturing an R-T-B sintered magnet according to claim 1 or 2, wherein:
the R-T-B sintered magnet material satisfies the following inequality (1),
[T]/55.85＞14[B]/10.8(1)
wherein [ T ] is the content of T in mass%, and [ B ] is the content of B in mass%.
4. The method of manufacturing an R-T-B sintered magnet according to claim 1 or 2, wherein:
the Ga content of the R-T-B sintered magnet raw material is 0 to 0.5 mass%.
5. The method of manufacturing an R-T-B sintered magnet according to claim 1 or 2, wherein:
the Nd content of the Pr-Ga alloy is less than the content of inevitable impurities.
6. A method for producing an R-T-B sintered magnet, comprising:
a step of preparing an R-T-B sintered magnet material, wherein the R-T-B sintered magnet material contains:
r: 27.5 to 35.0 mass%, wherein R is at least one of rare earth elements and essentially contains Nd,
b: 0.80 to 0.99% by mass,
ga: 0 to 0.8% by mass,
m: 0 to 2 mass%, wherein M is at least one of Cu, Al, Nb and Zr,
the balance of T and inevitable impurities, wherein T is Fe or Fe and Co;
preparing a Pr-Ga alloy;
a step of subjecting the Pr-Ga alloy to a heat treatment at a temperature 230 ℃ or higher and not higher than the melting point of the Pr-Ga alloy for 30 minutes or longer and 10 hours or shorter, and pulverizing the Pr-Ga alloy after the heat treatment, thereby obtaining a diffusion source composed of particles of an intermetallic compound having an average crystal grain size of more than 3 μm; and
a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface to the inside of the R-T-B sintered magnet material,
the Pr-Ga alloy is an alloy prepared by a strip casting method.
7. A method for producing an R-T-B sintered magnet, comprising:
a step of preparing an R-T-B sintered magnet material, wherein the R-T-B sintered magnet material contains:
r: 27.5 to 35.0 mass%, wherein R is at least one of rare earth elements and essentially contains Nd,
b: 0.80 to 0.99% by mass,
ga: 0 to 0.8% by mass,
m: 0 to 2 mass%, wherein M is at least one of Cu, Al, Nb and Zr,
the rest of T and inevitable impurities, wherein T is Fe or Fe and Co,
a step for pulverizing a Pr-Ga alloy to prepare Pr-Ga alloy powder;
a step of subjecting the Pr-Ga alloy powder to a heat treatment at a temperature which is 230 ℃ or higher and not higher than the melting point of the Pr-Ga alloy powder and not higher than the melting point thereof for 30 minutes or more and not higher than 10 hours or less to obtain a diffusion source composed of particles of an intermetallic compound having an average crystal grain diameter of more than 3 μm from the Pr-Ga alloy powder; and
a diffusion step of disposing the R-T-B sintered magnet material and the diffusion source in a processing vessel, and heating the R-T-B sintered magnet material and the diffusion source at a temperature exceeding 600 ℃ and up to 950 ℃ in a vacuum or inert gas atmosphere to diffuse Pr and Ga contained in the diffusion source from the surface into the inside of the R-T-B sintered magnet material;
the Pr-Ga alloy is an alloy prepared by a strip casting method.
8. The method of manufacturing an R-T-B sintered magnet according to claim 6 or 7, wherein:
the R-T-B sintered magnet material satisfies the following inequality (1),
[T]/55.85＞14[B]/10.8(1)
wherein [ T ] is the content of T in mass%, and [ B ] is the content of B in mass%.
9. The method of manufacturing an R-T-B sintered magnet according to claim 6 or 7, wherein:
the Ga content of the R-T-B sintered magnet raw material is 0 to 0.5 mass%.
10. The method of manufacturing an R-T-B sintered magnet according to claim 6 or 7, wherein:
the Nd content of the Pr-Ga alloy is less than the content of inevitable impurities.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017-187702 | 2017-09-28 | ||
| JP2017-187698 | 2017-09-28 | ||
| JP2017187702A JP6939337B2 (en) | 2017-09-28 | 2017-09-28 | Manufacturing method of RTB-based sintered magnet |
| JP2017-187703 | 2017-09-28 | ||
| JP2017187698A JP6946904B2 (en) | 2017-09-28 | 2017-09-28 | Diffusion source |
| JP2017187703A JP6939338B2 (en) | 2017-09-28 | 2017-09-28 | Manufacturing method of RTB-based sintered magnet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109585151A CN109585151A (en) | 2019-04-05 |
| CN109585151B true CN109585151B (en) | 2021-06-29 |
Family
ID=65919943
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811137401.6A Active CN109585151B (en) | 2017-09-28 | 2018-09-28 | Method for producing R-T-B sintered magnet and diffusion source |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109585151B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111243811B (en) * | 2020-02-29 | 2021-07-30 | 厦门钨业股份有限公司 | Neodymium-iron-boron material and preparation method and application thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101425354A (en) * | 2007-10-29 | 2009-05-06 | 沈阳新橡树磁性材料有限公司 | Cheap fast quenching rare-earth permanent magnetic alloy magnetic powder |
| CN107077965A (en) * | 2015-07-30 | 2017-08-18 | 日立金属株式会社 | The manufacture method of R T B based sintered magnets |
-
2018
- 2018-09-28 CN CN201811137401.6A patent/CN109585151B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101425354A (en) * | 2007-10-29 | 2009-05-06 | 沈阳新橡树磁性材料有限公司 | Cheap fast quenching rare-earth permanent magnetic alloy magnetic powder |
| CN107077965A (en) * | 2015-07-30 | 2017-08-18 | 日立金属株式会社 | The manufacture method of R T B based sintered magnets |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109585151A (en) | 2019-04-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP6555170B2 (en) | R-Fe-B sintered magnet and method for producing the same | |
| JP5304907B2 (en) | R-Fe-B fine crystal high density magnet | |
| JP6051892B2 (en) | Method for producing RTB-based sintered magnet | |
| JP6488976B2 (en) | R-T-B sintered magnet | |
| CN105957680B (en) | Rare earth cobalt permanent magnet | |
| JP6221233B2 (en) | R-T-B system sintered magnet and manufacturing method thereof | |
| JP2019169542A (en) | Method for manufacturing r-t-b based sintered magnet | |
| CN109997203A (en) | R-Fe-B system sintered magnet and its manufacturing method | |
| CN109585152B (en) | Method for producing R-T-B sintered magnet and diffusion source | |
| JP6051922B2 (en) | Method for producing RTB-based sintered magnet | |
| CN107665769B (en) | Method for producing R-T-B sintered magnet | |
| JP6939339B2 (en) | Manufacturing method of RTB-based sintered magnet | |
| JP6946905B2 (en) | Diffusion source | |
| JP7424126B2 (en) | RTB series permanent magnet | |
| CN109585151B (en) | Method for producing R-T-B sintered magnet and diffusion source | |
| JP6939337B2 (en) | Manufacturing method of RTB-based sintered magnet | |
| CN109585108B (en) | Method for producing R-T-B sintered magnet and diffusion source | |
| JP2021150547A (en) | Method for manufacturing r-t-b based sintered magnet | |
| JP6221246B2 (en) | R-T-B system sintered magnet and manufacturing method thereof | |
| JP2019062152A (en) | Diffusion source | |
| CN109585153B (en) | Method for producing R-T-B sintered magnet and diffusion source | |
| JP6939338B2 (en) | Manufacturing method of RTB-based sintered magnet | |
| CN111489874A (en) | Method for producing R-T-B sintered magnet | |
| JP6946904B2 (en) | Diffusion source | |
| JP7380369B2 (en) | Manufacturing method of RTB sintered magnet and alloy for diffusion |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |