JP5692940B2 - α + β-type or β-type titanium alloy and method for producing the same - Google Patents

Description

  The present invention relates to a titanium alloy, in particular, a titanium alloy having a composition excellent in mechanical properties such as strength and hardness as compared with a Ti-6Al-4V alloy and the like, which cannot be produced by a conventional melting method, and The present invention also relates to a titanium alloy manufacturing method capable of manufacturing the alloy at low cost.

  Titanium alloys are not only used for aircraft but also for consumer use, and the demand is growing year by year. Above all, aircraft alloys have high demands on quality and function, so high quality is the top priority, and manufacturing cost reduction is often the next issue.

  However, reducing the production cost of titanium alloys by improving the labor of the alloy manufacturing process and improving yields increases the amount of light titanium alloy used, that is, reduces the energy load of machine equipment operation. It is thought to be in line with social demands.

  In particular, among aircraft titanium alloys, Ti-6Al-4V alloy (hereinafter sometimes referred to as 64 alloy) has been used for a long time because of its excellent mechanical properties. However, since the 64 alloy has poor workability, there is a problem that it is difficult to apply to a complex part.

  Under such circumstances, a Ti-4.5Al-3V-2Fe-2Mo alloy (so-called SP700) was developed to improve the workability of the 64 alloy. In addition, Ti-10V-2Fe-3Al (so-called 10-2-3 alloy) and Ti-15V-3Cr-3Al-3Sn (so-called 15-3-3) which have further increased strength while maintaining the elongation of 64 alloy. 3-3 alloy) has been developed. However, any alloy of SP700, 10-2-3, and 15-3-3-3-3 tends to segregate vanadium, iron, and the like, and further improvements are required.

  On the other hand, it has been reported that the workability of a titanium material is further improved by adding 1% of copper to pure titanium (for example, see Non-Patent Document 1). However, copper has a large segregation in titanium, and it is difficult to add more than 1% to titanium, and there is a restriction in further improving the properties of the alloy, and improvement is required.

  On the other hand, a technique for producing 64 alloy, which is called an elementary powder mixing method, using metal powder as a raw material is also known (see, for example, Patent Document 1 and Non-Patent Document 2). The elementary powder mixing method is a method in which powders of constituent elements constituting the target alloy are separately prepared, and a composite powder obtained by uniformly mixing these powders is used as a starting material of the titanium alloy.

  However, the raw powder mixing method is promising on the test scale, but the cost hurdle is high on the operation scale, and it is limited to be put to practical use. Moreover, titanium alloys containing high concentrations of copper have been reported. There is no example.

  In addition, about the point of the cost of titanium powder, it originates in the pure titanium material to be used being expensive, and the further improvement is calculated | required.

  Thus, a titanium alloy that is superior in mechanical properties to 64 alloy and a method for producing the alloy at low cost are desired.

JP-A-5-009630 (text)

Fujii, Takahashi, Mori, Kawakami, Kunieda, Otsuka, Materia Vol. 48 (2009), (11), pp. 547-554 (text) Saito, Furuta, Toyota Central R & D Review Vol.29 (1994), (3), 49-60 (text)

  The object of the present invention is to provide a copper-containing titanium alloy having a composition that cannot be realized by a conventional method in which copper is segregated in titanium without segregation as described above, and has improved strength and hardness. There is. In addition, another object of the present invention is to provide a method for producing the copper-containing titanium alloy at a lower cost than conventional methods.

  Various studies have been made in view of such circumstances, and it has been found that a titanium alloy is produced by a powder metallurgy method instead of a melting method, a titanium alloy is made into a titanium alloy powder by a hydrodehydrogenation method, and the titanium As a mixed powder obtained by adding copper powder to an alloy powder, the present inventors have found that a titanium alloy having strength, elongation and hardness superior to those of the conventional method can be produced by pressure forming this under heating. It came to complete. Here, in the present invention, the above-mentioned “press forming under heating” means press forming a mixed powder obtained by adding copper powder to titanium powder while warm or hot. is there.

  As a result, it was found that a titanium alloy containing a high concentration of copper, which was difficult to manufacture by the conventional method, could be manufactured, and that a titanium alloy having a uniform structure with little segregation of copper could be manufactured at low cost, and the present invention was completed. It was.

  Furthermore, the titanium alloy manufactured by the above-described method has an effect of not only showing high strength but also excellent hardness in comparison with the titanium alloy manufactured by the conventional method because of less concentration segregation of alloy components. It is what you play.

That is, the α + β type or β type titanium alloy according to the present invention contains 1 to 10 mass% copper by adding copper powder , and the crystal phase thereof is either β phase or α phase and β phase, is composed of the crystal phase is 100μm or less of crystal grains, and the copper concentration per 1 mm ³ of any site of the crystal phase, Ri near within ± 40 mass% as compared to any other site, at least aluminum Α + β type or β type titanium alloy containing vanadium and α + β type or β type titanium alloy containing aluminum and vanadium and containing at least one element selected from molybdenum, iron, chromium and tin. The alloy type is mass%,
(90-99) (Ti-6Al-4V)-(1-10) Cu,
Ti- (9-10) V- (1.8-2) Fe- (2.7-3) Al- (1-10) Cu,
Ti- (13.5-15) V- (2.7-3) Cr- (2.7-3) Al- (2.7-3) Sn- (1-10) Cu,
Ti- (4.1-4.5) Al- (2.7-3) V- (1.8-2) Fe- (1.8-2) Mo- (1-10) Cu,
Ti- (4.5-5) Al- (4.5-5) V- (4.5-5) Mo- (2.7-3) Cr- (1-10) Cu,
Ti- (4.5-5) Al- (3.6-4) V- (0.5-0.6) Mo- (0.3-0.4) Fe- (1-10) Cu
It is either of these .

  In addition, the α + β type or β type titanium alloy according to the present invention is preferably obtained by pressure forming a mixed powder composed of copper powder and titanium alloy powder under heating. is there.

Furthermore, in the α + β type or β type titanium alloy according to the present invention, the titanium alloy powder is produced using a titanium alloy as a raw material. The titanium alloy includes aluminum, vanadium, molybdenum, iron, chromium, It is characterized in that at least one element is contained from tin.

The method for producing an α + β-type titanium alloy or β-type titanium alloy according to the present invention is a method for producing the aforementioned α + β-type titanium alloy or β-type titanium alloy containing copper, comprising 1 to 10 mass% copper powder and at least aluminum. Titanium alloy powder containing aluminum and vanadium, or titanium alloy powder containing aluminum and vanadium and containing at least one element selected from molybdenum, iron, chromium, and tin. It is characterized by being pressure-molded to form a dense molded body.

  In the α + β-type titanium alloy or the β-type titanium alloy manufacturing method according to the present invention, the pressure molding temperature (Tw (° C.)) under the above heating is (Td−100 ° C.) <Tw <(Td + 100 ° C.) (Where Td (° C.) represents the β transformation point of the titanium alloy to be pressed).

Furthermore, in the manufacturing method of the α + β type titanium alloy or β type titanium alloy according to the present invention, the titanium alloy powder is manufactured using a titanium alloy as a raw material, and the titanium alloy includes aluminum, vanadium, It is characterized in that it contains at least one metal element selected from molybdenum, iron, chromium and tin.

  According to the method for producing an α + β type or β type titanium alloy according to the present invention described above, it has a high concentration of copper that could not be produced by the conventional method, and has a composition free from segregation of copper, and further has a strength. In addition, there is an effect that a titanium alloy which is a hard material can be manufactured at low cost.

  As a result, the titanium alloy according to the present invention has an effect that it can be suitably used in the fields of high-strength mechanical parts, medical materials, and aircraft materials.

It is a flowchart figure which shows the manufacturing method of the alpha + beta type or beta type titanium alloy which concerns on this invention. It is a microscope picture which shows the structure | tissue of the sintered compact in an Example, (a) shows Example 2-1 and (b) shows the sintered compact of Example 2-2. It is an EPMA image which shows element distribution of Ti, V, Al, and Cu in an Example.

The best embodiment of the present invention will be described below with reference to the drawings.
The α + β type or β type titanium alloy according to the present invention contains 1 to 10 mass% copper, the crystal phase thereof is either β phase or α phase and β phase, and is composed of crystal grains of 100 μm or less, In addition, the copper concentration per mm ^{3 at} an arbitrary portion of the crystal phase is within ± 40 mass % as compared with other arbitrary portions.

In the conventional powder metallurgy method, a difference in concentration may occur between different parts in the alloy due to the fact that it is manufactured by adding copper powder to an alloy powder manufactured using a titanium alloy as a raw material. is there. However, the titanium alloy according to the present invention is characterized in that the copper concentration per 1 mm ^{3 in} any part of the crystal phase is suppressed within ± 40 mass % compared to other arbitrary parts. The entire organization is kept sufficiently uniform.

  In addition, the α + β type or β type titanium alloy according to the present invention is characterized by being manufactured by press-forming under heating a titanium alloy powder containing 1 to 10 mass% copper powder.

  Here, in the present invention, the titanium alloy powder containing 1 to 10 mass% copper powder means a composite powder obtained by adding and mixing separately prepared copper powder to titanium alloy powder not containing copper powder. .

  In the present invention, titanium alloy powder containing aluminum or vanadium is preferably used as the titanium alloy powder. Preferred examples of such alloy powder include Ti-6Al-4V alloy powder and Ti-3Al-2.5V alloy powder.

In addition to aluminum and vanadium, molybdenum or iron, or alloy powder appropriately containing chromium or tin may be used. These typical alloy powders are listed below.
Ti-10V-2Fe-3Al alloy powder,
Ti-15V-3Al-3Al-3Cr-3Sn alloy powder,
Ti-4.5Al-3V-2Fe-2Mo alloy powder,
Ti-5Al-5V-5Mo-3Cr alloy powder,
Ti-5Al-4V-0.6Mo-0.4Fe alloy powder

  The above-mentioned titanium alloy powder is preferably produced by using ingot cutting chips or scrap as a raw material, and this is manufactured by a hydrodehydrogenation method (hereinafter sometimes referred to as “HDH method”). It is.

  FIG. 1 shows a preferred embodiment of a process related to production of a titanium alloy according to the present invention. As the titanium alloy raw material used in the present invention, an alloy scrap or a titanium alloy ingot having a desired component from the beginning, such as a titanium alloy chip, a titanium alloy forged piece, or an end material of a titanium alloy rod, can be used. .

  By using the above-described alloy scrap material as a raw material, the production cost of titanium alloy powder can be effectively suppressed. These titanium alloy scraps or titanium alloy ingots (hereinafter sometimes simply referred to as “titanium alloy raw materials”) are preferably adjusted in advance to a predetermined length or size.

  For example, in the case of alloy chips, it is preferable to cut in advance to a length of 100 mm or less. By cutting into the above lengths, there is an effect that the subsequent hydrogenation process can be efficiently advanced. In addition, block-shaped alloy scraps such as forged pieces do not need to be pretreated as long as they are large enough to enter a hydrogenation furnace. When the alloy raw material is a titanium alloy ingot, it is preferable to use chips.

  The titanium alloy raw material adjusted as described above is subjected to a hydrotreating process in a hydrogen atmosphere. The hydrogenation treatment is preferably performed in a temperature range of 500 to 650 ° C. Since the hydrogenation reaction of the alloy raw material is an exothermic reaction, there is no need for a temperature raising operation by a heating furnace with the progress of the hydrogenation reaction, and there is an effect that the hydrogenation reaction can proceed spontaneously. is there.

  The hydrogenated titanium alloy raw material (hereinafter sometimes simply referred to as “titanium hydride alloy”) is cooled to room temperature and then ground and sieved to a predetermined particle size in an inert atmosphere such as argon gas. It is preferable to separate.

  Subsequently, the titanium hydride alloy powder pulverized and sieved into a powder form is preferably heat-treated to a high temperature range in an atmosphere maintained in a reduced pressure atmosphere.

  The dehydrogenation treatment temperature is preferably performed while evacuating in a temperature range of 500 ° C to 800 ° C. Since the dehydrogenation reaction is an endothermic reaction unlike the above-described hydrogenation treatment reaction, a heating operation is required until generation of hydrogen from the titanium hydride alloy powder disappears.

  By the above operation, the titanium alloy powder according to the present invention can be obtained. The titanium alloy powder according to the present invention is preferably sized in the range of 1 to 300 μm, more preferably 5 to 150 μm. If the particle diameter is coarser than this range, the density of the final alloy tends to be difficult to increase. On the other hand, if finer than this range, the bulk density becomes low and it is easy to oxidize. Inconvenience arises.

  The titanium alloy powder obtained after completion of the dehydrogenation treatment may be sintered with each other. In this case, it is preferable to appropriately perform a crushing treatment.

  In this invention, 1-10 mass% copper powder is mix | blended with respect to the titanium alloy powder manufactured by the said method.

  By blending 1 to 10 mass% copper powder with respect to the titanium alloy powder, the strength and hardness of the titanium alloy material obtained by pressure forming using the alloy powder as a raw material is maintained at a high level. There is an effect that it is possible.

  As for the particle size of the copper powder blended in the titanium alloy powder, it is preferable to use a particle size adjusted in the range of 1 to 300 μm. More preferably, it is preferable to use copper powder in the range of 1 to 50 μm.

  Since it is more advantageous to use a finer copper powder to produce a titanium alloy powder having a uniform composition, the average particle size (d50) of the copper powder is 10 to 40 μm in the above-described range of the particle size 1 to 50 μm. It is preferable to adjust so as to be in the range.

  In the present invention, it is preferable that the copper-added titanium alloy powder obtained by the above-described method is further uniformly mixed and then pressure-formed under heating.

  For the pressure molding used in the present invention, known techniques such as HIP, hot press, CIP-HIP, and extrusion under heating can be applied. Especially when extrusion under heating is used, There is also an effect that sintering and shape forming can be performed simultaneously in a short time, and an excellent effect in terms of productivity is also achieved.

  In the present invention, the titanium alloy powder blended with the copper powder is preferably subjected to pressure molding under heating after filling into a metal capsule.

  The titanium alloy material obtained by extrusion of titanium alloy powder blended with copper powder filled in a metal capsule is a titanium alloy containing copper with a high composition that could not be produced by the conventional method, and the segregation of copper is It exhibits excellent mechanical properties such as a small amount, strength, and hardness.

  The pressure molding temperature (Tw) described above is preferably in the range of (Td−100 ° C.) <Tw <(Td + 100 ° C.). Here, Td means the β transformation point of the titanium alloy to be subjected to pressure forming. By heating the titanium alloy powder in advance within the above range, there is an effect that the pressure forming can be smoothly advanced.

When the pressure molding temperature is lower than (Td-100 ° C), the deformation resistance of the titanium alloy powder is large, and it is difficult to fully densify the titanium alloy powder even after the pressure molding. is there.
In particular, when pressure molding is performed by extrusion, the material may be clogged in the die, which is not preferable.

  On the other hand, in the present invention, when the pressure molding temperature is higher than (Td + 100 ° C.), the crystal grain of the titanium alloy material tends to be coarsened to 100 μm or more. This is undesirable because it adversely affects the mechanical properties of the material.

  In addition, when the pressure molding temperature according to the present invention is pressure molding in the temperature range of (Td-100 ° C.) to Td, that is, the α + β region, the crystal structure of the pressure-formed titanium alloy material is Since it is uniform and refined, it is not only strong and hard, but also exhibits excellent mechanical properties with a good balance between tensile strength and elongation.

The titanium alloy according to the present invention contains copper having a composition of 1 to 10 mass%, and the value of the copper concentration per 1 mm ³ in any part of the alloy is the concentration of copper in any other part. The value is within ± 40 mass % with respect to the value.

  The above aspect means that the copper in the titanium alloy according to the present invention is almost uniformly distributed.

  Among the titanium alloys having such a structure, when a Ti-6Al-4V alloy is taken as an example, the tensile strength is 1400 to 1550 MPa, the elongation is 2 to 7%, and the tensile strength is superior to that of a conventional alloy. This has the effect of showing excellent values not only for strength but also for elongation.

  Titanium alloys with such excellent mechanical properties were produced by densifying the alloy powder obtained by pulverizing the alloy obtained by the melting method called the pre-alloy method, among other powder methods. Is a preferred embodiment.

  Here, the “prealloy method” means that a powder produced using an alloy produced by the melting method as a raw material is used as a raw material for sintering, and metal powder composed of a single component is prepared separately. It is opposed to the elementary powder mixed powder obtained by uniformly mixing these metal powders.

  Among the above powder methods, the use of pre-alloy powder as a raw material has the effect that a titanium alloy having a uniform alloy composition can be produced.

  This fine densification condition for realizing the above-described characteristics will be described below by taking extrusion as an example.

First, a titanium alloy powder and a copper powder having a target composition are prepared, and after this is uniformly mixed, the mixed powder is charged into a metal capsule, and then the inside of the capsule is brought to a vacuum state of 10 ⁻¹ Torr or less. After that, it is preferable to perform pressure molding by HIP, CIP-firing, extrusion or the like. It is also preferable that the powder is filled in a die and hot pressed at a vacuum degree of 10 ⁻² Torr or less.

  The pressure molding temperature (Tw) under heating is preferably in the range of (Td−100 ° C.) <Tw <(Td + 100 ° C.).

  Thus, pressure molding under heating in the present invention can be achieved by using a known method such as HIP, hot press, CIP-HIP, or extrusion under heating.

  In the present invention, the ratio of the cross-sectional area of the extruded titanium alloy material to the cross-sectional area of the capsule charged in the extrusion apparatus (in the pressure molding by hot extrusion among the pressure molding under heating) ( Hereinafter, it may be simply referred to as “extrusion ratio”) in the range of 1/10 to 1/30.

  By setting the extrusion ratio within the above-mentioned range, the degree of flow of the capsule containing the titanium alloy powder is controlled, the degree of forging of the extruded titanium alloy material can be adjusted, and more favorable mechanical properties are imparted. It has the effect of doing.

  Machines applied to titanium alloy materials manufactured by applying a forging process under heating such as rolling and forging at the above-mentioned cross-sectional area ratio for pressure molded bodies such as HIP, hot press, CIP-HIP, etc. This has the effect of improving the target characteristics.

  In addition, it is preferable to isolate | separate the capsule which has coat | covered the titanium alloy material manufactured by methods, such as HIP in this invention, CIP-HIP, and the extrusion under a heating, by cutting or pickling. The titanium alloy material from which the capsules are thus separated may be heated again to a high temperature in a vacuum atmosphere.

  The strength of the titanium alloy material that has undergone the above-described treatment is remarkably excellent, and has fine crystal grains and is reinforced by uniformly distributed Cu. Therefore, it is suitable for structural materials such as high-strength mechanical parts. The effect that it can be done is produced.

  That is, the strength of the titanium alloy material containing copper according to the present invention not only shows a value as high as 10 to 30%, but also uses titanium alloy scrap as a raw material. In this case, the raw material cost can be reduced, and as a result, the cost of the titanium alloy material as the final product can be reduced by 50 to 70% compared to the conventional case.

  Moreover, the titanium alloy material according to the present invention has an effect of showing a value as high as 10 to 30% in terms of hardness as compared with a material to which copper is not added.

  The titanium alloy according to the present invention has excellent mechanical properties as described above. As a result, the titanium alloy can be suitably applied not only to industrial precision machine parts, but also to medical materials. In addition, the aircraft parts that require not only abrasion resistance but also can be suitably used.

  In addition, although the said titanium alloy containing copper can be manufactured also by a melt | dissolution method, segregation is remarkable and it is difficult to manufacture a practical alloy.

  The titanium alloy material produced in the present invention preferably contains at least aluminum and vanadium, and may contain molybdenum, iron, chromium, or tin as appropriate. . These representative alloys are listed below. However, alloys that can be produced in the present invention are not limited to these, and can be applied to various titanium alloys.

Ti- (9-10) V- (1.8-2) Fe- (2.7-3) Al- (1-10) Cu,
Ti- (13.5-15) V- (2.7-3) Cr- (2.7-3) Al- (2.7-3) Sn- (1-10) Cu,
Ti- (4.1-4.5) Al- (2.7-3) V- (1.8-2) Fe- (1.8-2) Mo- (1-10) Cu,
Ti- (4.5-5) Al- (4.5-5) V- (4.5-5) Mo- (2.7-3) Cr- (1-10) Cu,
Ti- (4.5-5) Al- (3.6-4) V- (0.5-0.6) Mo- (0.3-0.4) Fe- (1-10) Cu.

  As described above, according to the present invention, it is a copper-containing titanium alloy having a composition that could not be manufactured by the conventional method, and there is no segregation of copper, and further, there is an effect that it is possible to provide a titanium alloy that is strong and hard. It plays. In addition, the titanium alloy can be efficiently produced at a lower cost than the conventional method.

Data according to Examples and Comparative Examples was collected under the following conditions.
1. material
1) 64 alloy powder
Manufacturing method: After manufacturing 64 alloy scrap by HDH method, pulverizing and sizing
Average particle diameter (d50): 52 μm
2) Copper powder
Manufacturing method: electrolytic copper powder, manufactured by JX Nippon Mining & Metals Co., Ltd., trade name 51-N
Average particle diameter (d50): 35 μm
3) Mixing ratio of copper powder to titanium alloy powder
1% to 10mass%
4) Mixing
The 64 alloy powder and copper powder were homogenized using a commercially available mixer.

2. Preliminary test
In order to determine the pressure molding conditions under heating, a sample was prepared by adding copper powder to 64 alloy powder by adding 0%, 3%, 5%, 7%, 10%, and β transformation point (Td) Deformation resistance at a temperature near the β transformation point (Td) was determined. The β transformation point (Td) was measured by measuring the electrical resistance by a four-terminal method while heating and heating the test piece in an argon gas atmosphere, and the temperature at which the temperature dependence of the electrical resistance change changed was taken as the transformation point. The apparatus used was an electrical resistance measuring device (trade name ARC-TER-1 type). The results were as follows.

  The β transformation point (Td) of 64 alloy (0% copper) reported in the literature is 995 ° C., which is almost equal to the value.

  Next, the deformation resistance at a temperature 30 ° C. lower than the β transformation point (Td) and β transformation point (Td) determined above and 50 ° C. higher than the β transformation point (Td) was determined. The measurement was performed by a compression test using a hot working reproduction device (Fuji Electric Koki Co., Ltd., Cermec Master Z). The results are shown below.

3. Extrusion
The extrusion temperature was determined in consideration of the pushing force of the extrusion apparatus and the deformation resistance of the material. A composite powder obtained by mixing 64% alloy powder with copper powder at 0%, 3%, 5%, 7% and 10% was filled in a mild steel capsule, and the inside was evacuated to 1 × 10 ⁻² Torr and sealed. The powder-encapsulated capsule was molded by hot extrusion as an example of pressure molding under heating. The heating temperature of each copper content at this time was set to the temperature described in Table 3. The heating time was 2 Hr. The heating temperature of each copper content alloy and the temperature difference from the β transformation point (Td) of the temperature are as shown in the table below.

4). Processing pressure-molded materials
Capsules remaining on the surface of the titanium alloy material produced by pressure forming under heating were dissolved and removed by pickling.

5. Measuring mechanical properties
1) Tensile strength measurement
An Instron tensile tester (model number: 5985 type) was used.
2) Crystal structure observation
A measuring instrument EPMA (model number: JXA-8100) manufactured by JEOL Ltd. was used.
3) Copper distribution in the crystal structure
A measuring instrument EPMA (model number: JXA-8100) manufactured by JEOL Ltd. was used.

[Example 1 / Comparative Example 1] (Difference in effect with and without addition of copper powder)
The mechanical characteristics in the case where copper powder was added to the 64 alloy powder and in the case where copper powder was not added were investigated. As shown in Table 4, it was confirmed that the addition of copper powder was superior in yield strength, tensile strength, and hardness. The copper-added alloy was slightly stretched particularly with a material having a copper content of 5% or more, which was considered to be due to the fact that the pressure forming temperature was in the β temperature range.

[Example 2 / Comparative Example 2] (Difference in pressure molding temperature)
The influence of the pressure forming temperature on the crystal structure of the sintered body obtained by pressure forming was examined for the Cu 5% added 64 alloy (beta transformation point: 950 ° C.).
In Example 2-1 and Example 2-2 in which the pressure molding temperature is in the range of the present invention, a mixed phase structure of β phase and α phase was observed as shown in FIG. On the other hand, in Comparative Example 2-1, in which the pressure molding temperature is outside the range of the present invention, the β phase in the crystal structure was coarsened. Further, in Comparative Example 2, the material was clogged in the die, and a pressure-molded material could not be obtained.

[Example 3] (Cu concentration distribution of manufactured titanium material)
In Example 2, the component concentration in the crystal structure of the titanium material produced by pressure molding was examined by EPMA. Respective X-ray images were obtained for Ti, Al, V, and Cu. The image is shown in FIG. 3 and the results are shown below. The numbers shown here are EPMA count numbers, and the sensitivity varies depending on each element. Therefore, in order to convert the count number into a concentration, the average count number is the nominal concentration of each element as shown in Table 6. A density correction coefficient was determined. Based on this correction coefficient, the existence ratio for each concentration was obtained as shown in Table 7 and Table 8. The minimum and maximum concentrations of each element were as follows.

Ti (average concentration 85.5%) has a minimum concentration of 74.8% and a maximum concentration of 96.3%.
Al (average concentration 5.7%) is the lowest concentration 3.8% to the highest concentration 8.6%
V (average density 3.8%) is the lowest density 3.0% to the highest density 4.8%
Cu (average concentration 5.0%) is a minimum concentration of 2.0% to a maximum concentration of 8.2%.

Although there is a region of composition that is nearly 100% away from the nominal value of the material when the Cu concentration is viewed microscopically, the average value of the Cu concentration at an arbitrary 1 mm ³ site is 4 regardless of how 1 mm ³ is set. 0.5% to 5.5%, within ± 10% of the nominal material value of 5%. That is, there is no macro segregation. Looking at the average value of the concentration of Al and V at an arbitrary 1 mm ³ site, Al is within a range of ± 8% with respect to the nominal value of the material, and V is within a range of ± 15% with respect to the nominal value of the material. Met.

[Comparative Example 3] (Production of alloy by elementary powder mixing method)
In Example 1, instead of 64 alloy powder, Example 1 was used except that a mixed powder obtained by weighing a predetermined amount of aluminum powder (60 wt%) and vanadium powder (40%) and mixing them uniformly was used. Under the same conditions, 64 copper-added alloy was produced.

  The mechanical properties of the produced 64 alloy were not significantly different from the results shown in Table 1 of Example 1. However, the production cost reached 2-3 times that of the material produced in Example 1. This was mainly derived from the difference in cost of the 64 alloy powder.

[Comparative Example 4] (Alloy by melting method)
In place of the alloy powder used in Example 1, 64 alloy ingots and electrolytic copper were prepared and mixed with 3, 5, and 10 wt% electrolytic copper, and then an alloy of 64 alloy with copper of φ100 using an electron beam melting furnace. Got.

  Test pieces were cut out from the copper-containing 64 alloy ingot, the mechanical properties were investigated, and the results are summarized in Table 8. The tensile strength of the ingot melted in the comparative example was 20% to 25% lower than that in Example 1.

In order to investigate the cause, the distribution state of copper in the ingot was investigated with a CX ray microanalyzer, and the Cu concentration became 0.3 to 0.5% and an average concentration over a wide area of 1 mm ³ or more. On the other hand, a 1/10 or more diluted region and a portion where the Cu concentration was 20% to 40% and concentrated 10 times or more of the average concentration were observed.

  From the above test results, it was confirmed that the titanium alloy according to the present invention has excellent mechanical properties as compared with a titanium alloy produced by a conventional melting method. Furthermore, by using the alloy powder produced by the pre-alloy method used in the present invention, the production cost is reduced by 30 to 40%, although it exhibits the same level of mechanical properties as the elementary powder mixing method. It was confirmed that it could be manufactured.

[Example 4] (5% Cu added to Ti-10V-2Fe-3Al alloy powder)
The cutting powder of the Ti-10V-2Fe-3Al alloy ingot was hydrogenated to produce a hydride of Ti-10V-2Fe-3Al alloy, which was pulverized and sieved to obtain an alloy powder having D50 = 50 μm. To this powder, 5% of the electrolytic copper powder used in Example 1 was added to obtain a mixed powder composed of Ti-10V-2Fe-3Al alloy powder and electrolytic copper powder. This mixed powder was enclosed in a mild steel capsule and subjected to hot extrusion. Extrusion was carried out after heating to 800 ° C. for 2 hours. Observation of the structure of the extruded material, tensile test, hardness measurement, and EPMA observation were performed. Table 9 shows the crystal grain size, yield strength, tensile strength, elongation, and hardness.

  From the X-ray mapping of EPMA, in the same manner as in Example 3, the correction coefficient was determined from the EPMA counts and average concentrations of Ti, V, Fe, Al, and Cu, and the concentration distribution of each component was determined. The results are shown in Table 10.

[Comparative Example 5] (Ti-10V-2Fe-3Al alloy powder, no copper powder added)
The Ti-10V-2Fe-3Al alloy powder produced in Example 4 was encapsulated in a mild steel capsule without adding copper powder, and subjected to hot extrusion. Extrusion conditions were the same as in Example 4. Observation of the structure of the extruded material, tensile test, and hardness measurement were performed. The results are shown in Table 9.

[Example 5] (Add 5% copper powder to Ti-15V-3Al-3Cr-3Sn alloy powder)
The cutting chips of the Ti-15V-3Al-3Cr-3Sn alloy ingot were hydrogenated to produce a hydride of Ti-15V-3Al-3Cr-3Sn alloy, which was pulverized and sieved to obtain an alloy powder having D50 = 50 μm. 5% of the electrolytic copper powder used in Example 1 was added to this powder to obtain a mixed powder composed of Ti-15V-3Al-3Cr-3Sn alloy powder and electrolytic copper powder. This mixed powder was enclosed in a mild steel capsule and subjected to hot extrusion. Extrusion was performed after heating to 750 ° C. for 2 hours. Observation of the structure of the extruded material, tensile test, hardness measurement, and EPMA observation were performed. Table 9 shows the crystal grain size, yield strength, tensile strength, elongation, and hardness.

  From the X-ray mapping of EPMA, in the same manner as in Example 3, the correction coefficient was determined from the respective EPMA counts and average concentrations of Ti, V, Al, Cr, Sn, and Cu, and the concentration distribution of each component was determined. The results are shown in Table 11.

[Comparative Example 6] (Ti-15V-3Al-3Cr-3Sn alloy powder, no copper powder added)
The Ti-15V-3Al-3Cr-3Sn alloy powder produced in Example 5 was encapsulated in a mild steel capsule without adding Cu powder and subjected to hot extrusion. Extrusion conditions were the same as in Example 5. Observation of the structure of the extruded material, tensile test, and hardness measurement were performed. The results are shown in Table 9.

[Example 6] (5% copper powder added to Ti-4.5Al-3V-2Fe-2Mo alloy powder)
The cutting chips of Ti-4.5Al-3V-2Fe-2Mon alloy ingot are hydrogenated to produce a hydride of Ti-4.5Al-3V-2Fe-2Mo alloy, pulverized and sieved to obtain an alloy powder of D50 = 50 μm. Obtained. 5% of the electrolytic copper powder used in Example 1 was added to this powder to obtain a mixed powder composed of Ti-4.5Al-3V-2Fe-2Mo alloy powder and electrolytic copper powder. This mixed powder was enclosed in a mild steel capsule and subjected to hot extrusion. Extrusion was carried out after heating to 880 ° C. for 2 hours. Observation of the structure of the extruded material, tensile test, hardness measurement, and EPMA observation were performed. Table 9 shows the crystal grain size, yield strength, tensile strength, elongation, and hardness.

  From the X-ray mapping of EPMA, in the same manner as in Example 3, the correction coefficient was obtained from the respective EPMA counts and average concentrations of Ti, Al, V, Fe, Mo, and Cu, and the concentration distribution of each component was obtained. The results are shown in Table 12.

[Comparative Example 7] (Ti-4.5Al-3V-2Fe-2Mo alloy powder, no copper powder added)
The Ti-4.5Al-3V-2Fe-2Mo alloy powder produced in Example 6 was encapsulated in a mild steel capsule without adding copper powder and subjected to hot extrusion. Extrusion conditions were the same as in Example 6. Observation of the structure of the extruded material, tensile test, and hardness measurement were performed. The results are shown in Table 9.

[Example 7] (Add 5% copper powder to Ti-5Al-5V-5Mo-3Cr alloy powder)
The cutting chips of Ti-5Al-5V-5Mo-3Cr alloy ingot were hydrogenated to produce a hydride of Ti-5Al-5V-5Mo-3Cr alloy, pulverized and sieved to obtain an alloy powder of D50 = 50 μm. 5% of the electrolytic copper powder used in Example 1 was added to this powder to obtain a mixed powder composed of Ti-5Al-5V-5Mo-3Cr alloy powder and copper powder. This mixed powder was enclosed in a mild steel capsule and subjected to hot extrusion. Extrusion was carried out after heating to 840 ° C. for 2 hours. Observation of the structure of the extruded material, tensile test, hardness measurement, and EPMA observation were performed. Table 9 shows the crystal grain size, yield strength, tensile strength, elongation, and hardness.

  From the X-ray mapping of EPMA, in the same manner as in Example 3, the correction coefficient was obtained from the respective EPMA counts and average concentrations of Ti, Al, V, Fe, Mo, and Cu, and the concentration distribution of each component was obtained. The results are shown in Table 13.

[Comparative Example 8] (Ti-5Al-5V-5Mo-3Cr alloy powder, no copper powder added)
The Ti-5Al-5V-5Mo-3Cr alloy powder produced in Example 7 was encapsulated in a mild steel capsule without adding copper powder and subjected to hot extrusion. Extrusion conditions were the same as in Example 7. Observation of the structure of the extruded material, tensile test, and hardness measurement were performed. The results are shown in Table 9.

[Example 8] (5% copper powder added to Ti-5Al-4V-0.6Mo-0.4 Fe alloy powder)
Ti-5Al-5V-5Mo-3 Fe alloy Ingot is cut from hydrogenated chips to produce Ti-5Al-4V-0.6Mo-0.4 Fe alloy hydride, pulverized and sieved, D50 = 50 μm alloy A powder was obtained. 5% of the electrolytic copper powder used in Example 1 was added to this powder to obtain a mixed powder composed of Ti-5Al-4V-0.6Mo-0.4 Fe alloy powder and copper powder. This mixed powder was enclosed in a mild steel capsule and subjected to hot extrusion. Extrusion was carried out after heating to 900 ° C. for 2 hours. Observation of the structure of the extruded material, tensile test, hardness measurement, and EPMA observation were performed. Table 9 shows the crystal grain size, yield strength, tensile strength, elongation, and hardness.

From the X-ray mapping of EPMA, in the same manner as in Example 3, the correction coefficient was determined from the respective EPMA counts and average concentrations of Ti, Al, V, Mo, Fe and Cu, and the concentration distribution of each component was determined. The results are shown in Table 14.

[Comparative Example 9] (Ti-5Al-4V-0.6Mo-0.4 Fe alloy powder, no copper powder added)
The Ti-5Al-4V-0.6Mo-0.4 Fe alloy powder produced in Example 8 was encapsulated in a mild steel capsule without adding copper powder and subjected to hot extrusion. Extrusion conditions were the same as in Example 8. Observation of the structure of the extruded material, tensile test, and hardness measurement were performed. The results are shown in Table 9.

The present invention relates to a titanium alloy by a powder method and a method for producing the same, and is a copper-containing titanium alloy having a composition that is difficult to manufacture by a conventional method, which is free from segregation of copper, and further has strength and is hard. Not only in terms of cost, it can also be manufactured at a lower cost than in the prior art.

Claims (4)

Containing 1-10 mass% copper by adding copper powder, the crystal phase is either β phase or α phase and β phase, the crystal phase is composed of crystal grains of 100 μm or less, and An α + β-type or β-type titanium alloy containing at least aluminum and vanadium having a copper concentration per mm ^{3 in} an arbitrary part of the crystal phase within ± 40 mass % as compared with any other part , or aluminum Α + β type or β type titanium alloy containing vanadium and at least one element selected from molybdenum, iron, chromium, and tin,
The alloy type is mass%,
(90-99) (Ti-6Al-4V)-(1-10) Cu,
Ti- (9-10) V- (1.8-2) Fe- (2.7-3) Al- (1-10) Cu,
Ti- (13.5-15) V- (2.7-3) Cr- (2.7-3) Al- (2.7-3) Sn- (1-10) Cu,
Ti- (4.1-4.5) Al- (2.7-3) V- (1.8-2) Fe- (1.8-2) Mo- (1-10) Cu,
Ti- (4.5-5) Al- (4.5-5) V- (4.5-5) Mo- (2.7-3) Cr- (1-10) Cu,
Ti- (4.5-5) Al- (3.6-4) V- (0.5-0.6) Mo- (0.3-0.4) Fe- (1-10) Cu
An α + β-type or β-type titanium alloy characterized by being either   2. The α + β type or β type titanium alloy according to claim 1, wherein the titanium alloy is obtained by pressure forming a mixed powder composed of copper powder and titanium alloy powder under heating. . It is a manufacturing method of the α + β type titanium alloy or β type titanium alloy according to claim 1, comprising 1 to 10% by mass of copper powder and titanium alloy powder containing at least aluminum and vanadium , or aluminum and vanadium, An α + β-type titanium alloy or β-type characterized in that a titanium alloy powder containing at least one element selected from molybdenum, iron, chromium, and tin is subjected to pressure forming under heating to form a dense compact. A method for producing a titanium alloy. The pressure molding temperature under heating (Tw (° C.)) is in the range of (Td−100 ° C.) <Tw <(Td + 100 ° C.) (where Td (° C.) is the pressure of the titanium alloy to be pressure molded. The method for producing an α + β-type titanium alloy or β-type titanium alloy according to claim 3 , wherein the method represents a β transformation point.