Titanium alloy and method for producing the same

Abstract

To provide a titanium alloy having improved strength, and to provide a method for producing the same.SOLUTION: The method for manufacturing a titanium alloy includes a preparation step of preparing an ingot that is composed of components consisting of Ti, Al, a metallic M1 and a metallic M2 and other inevitable impurities and has a B2 structure and has a melting point Tm (K), a homogenizing step of homogenizing the ingot by holding the ingot at a first heat treatment temperature T1 (K) satisfying Tm-300 <T1 <Tm for 0.5 hours or more, and a forming step of forming a crystal phase having a B2 structure by holding the homogenized ingot at a second heat treatment temperature T2 (K) for 0.1 hours or more. The content a (at%) of Al in the components satisfies 0.5 <a <30. The metallic M1 is one or more elements selected from the group consisting of V, Nb, Mo, and Zr. The metallic M2 is one element selected from the group consisting of Ru, Sc, Ni, Co, Rh, Pd, Pt, Au, and Ir.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a titanium alloy and a method for producing the same. [Background technology]

[0002] Currently, research into titanium alloys is being conducted worldwide (see, for example, Non-Patent Documents 1 and 2). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] SA Kube et. al., Acta Mater. 265 (2024) 119628. [Non-patent document 2] Y. Yamabe-Mitarai et. al., J. Alloys Compd., 911 (2022) 164849. Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have come to recognize the following problem: The present inventors have focused on TiAl-based titanium alloys and have come to the conclusion that the strength of titanium alloys can be improved by forming a structure in which a crystalline phase having a BCC structure (hereinafter also referred to as "BCC phase") and a crystalline phase having a B2 structure (hereinafter also referred to as "B2 phase") coexist.

[0005] The present invention has been made in view of the above circumstances, and one of its exemplary objects is to provide a titanium alloy having improved strength and a method for producing the same. [Means for solving the problem]

[0006] One aspect of the present invention is a method for manufacturing a titanium alloy. The method for manufacturing the titanium alloy comprises a component consisting of Ti, Al, metal M1, and metal M2, as well as other inevitable impurities, and is capable of generating a crystal phase having a B2 structure. A preparation step of preparing an ingot having a melting point Tm (K); a homogenization step of holding the ingot at a first heat treatment temperature T1 (K) satisfying Tm - 300 < T1 < Tm for 0.5 hours or more to homogenize the ingot and obtaining a homogenized ingot having a BCC structure; and a generation step of holding the ingot homogenized in the homogenization step at a second heat treatment temperature T2 (K) for 0.1 hours or more to generate a crystal phase having a B2 structure. The content a (at%) of Al in the component satisfies 0.5 < a < 30. Metal M1 is one or more elements selected from the group consisting of V, Nb, Mo, and Zr. Metal M2 is one element selected from the group consisting of Ru, Sc, Ni, Co, Rh, Pd, Pt, Au, and Ir.

[0007] Another aspect of the present invention is a titanium alloy. The titanium alloy consists of a component consisting of Ti, Al, metal M1, and metal M2, as well as other inevitable impurities. Further, the titanium alloy has a BCC phase which is a crystal phase having a BCC structure and a B2 phase which is a crystal phase having a B2 structure. The content a (at%) of Al in the component satisfies 0.5 < a < 30. Metal M1 is one or more elements selected from the group consisting of V, Nb, Mo, and Zr. Metal M2 is one element selected from the group consisting of Ru, Sc, Ni, Co, Rh, Pd, Pt, Au, and Ir. The BCC phase and the B2 phase form a coherent structure. The content d (vol%) of the B2 phase in the titanium alloy satisfies 30 < d < 80.

[0008] In addition, any combination of the above components, and those obtained by converting the expression of the present invention between methods, alloys, etc. are also effective as aspects of the present invention.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a titanium alloy with improved strength and a method for manufacturing the same.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is a diagram for explaining the BCC structure and the B2 structure in a titanium alloy. [Figure 2] 1 is a flowchart showing the flow of a method for producing a titanium alloy according to one embodiment of the present invention. [Figure 3] 1 is an SEM image of a plate that has been homogenized. [Figure 4] 1 is an SEM image of Sample 1. [Figure 5] 1 is an SEM image of sample 2. [Figure 6] 1 is an SEM image of sample 3. [Figure 7] This is a TEM image of sample 2 observed at further magnification. [Figure 8] 1 is an SEM image of sample 4. [Figure 9] 1 is an SEM image of Sample 5. [Figure 10] FIG. 1 is a diagram showing an XRD pattern of a sample according to an example. [Figure 11] FIG. 1 is a diagram showing the results of measuring the Vickers hardness of Samples 1 to 5 at room temperature. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, identical elements are designated by the same reference numerals, and duplicate descriptions will be omitted where appropriate. In this specification and the drawings, multiple components having substantially the same functional configuration may be distinguished by adding different letters to the same reference numeral. However, when there is no need to particularly distinguish between multiple components having substantially the same functional configuration, the multiple components will be designated by the same reference numerals only.

[0012] (background) In jet engines used in aircraft, the temperature rises from the fan toward the rear, with exhaust gases exceeding 1000°C flowing through the turbine in particular. The current operating temperature limit for titanium alloys is around 600°C, making it difficult to use titanium alloys as materials for turbines and other components. For this reason, nickel-based superalloys are used for turbines, which are subject to high temperatures.

[0013] Since the specific gravity of nickel-based superalloys is about twice that of titanium alloys, the use of nickel-based superalloys reduces the thermal efficiency of jet engines compared to titanium alloys. For this reason, titanium alloys that can be used at temperatures above 600°C are required.

[0014] Currently used titanium alloys are composed of a crystalline phase with a solid solution HCP structure and a BCC phase, but it is difficult to obtain mechanical properties sufficient to withstand use at temperatures above 600°C through solid solution strengthening alone.

[0015] Nickel-based superalloys used in jet engine turbines are known to have excellent high-temperature mechanical properties due to the cubic precipitation of ordered Ni3Al in a crystalline phase with an FCC structure.

[0016] Titanium alloys have a BCC structure, not an FCC structure. Coherent precipitation of the BCC phase in the B2 phase has also been reported for titanium alloys (TE Whitfield et. al., Materialia, 13 (2020) 100858.). Similar results have also been reported for titanium alloys such as TiAlTaZr, TiAlTaZrNb, TiAlTaZrNb, TiAlCoNiFeCr, and AlCoCrFeNiTi.

[0017] The inventors are attempting to develop titanium alloys with mechanical properties equal to or superior to those of currently used titanium alloys by coherently precipitating the B2 phase within the BCC phase, thereby improving the mechanical properties at temperatures above 600°C.

[0018] (Titanium alloy) The titanium alloy according to an embodiment of the present invention is composed of components including Ti, Al, metal M1, and metal M2, and other inevitable impurities, and has a BCC phase which is a crystal phase having a BCC structure and a B2 phase which is a crystal phase having a B2 structure. Metal M1 is one or more elements selected from the group consisting of V, Nb, Mo, and Zr, and metal M2 is one element selected from the group consisting of Ru, Sc, Ni, Co, Rh, Pd, Pt, Au, and Ir.

[0019] FIG. 1 is a diagram for explaining the BCC structure and the B2 structure in the titanium alloy. FIG. 1 shows a body-centered cubic lattice. For example, taking the case where metal M2 is Ru, Ru forms a B2 structure with Ti in a 1:1 ratio. When Ru is located at the site C1 at the center of the cube shown in FIG. 1, Ti is located at the site C2 at each vertex of the cube. Ru can form a B2 structure with Al, V, Nb, and Zr in a 1:1 ratio, for example. Therefore, the B2 structure is a regularized structure where Ru is located at site C1, and any one of Ti, Al, and metal M1 (V, Nb, and Zr) is located at the remaining site C2. On the other hand, in the BCC structure, at sites C1 and C2, Ti, Al, metal M1, and metal M2 are randomly located, resulting in an irregular structure. Here, the example where metal M2 is Ru has been explained, but Ni, Co, Rh, Pd, Pt, Au, and Ir can also form a B2 structure with Ti respectively. Further, Sc, Ni, Co, Rh, Pd, Pt, Au, and Ir can form a B2 structure with Al respectively.

[0020] Excluding the inevitable impurities of the titanium alloy, the components are represented as Ti ,

[0021] , Al a1 M1 b1 M2 c1 In this embodiment, the content a1 (at%) of Al in this component satisfies 0.5 < a1 < 30. However, a1 may satisfy 0 < a1 ≤ 0.5, and when b1 ≠ 0 and c1 ≠ 0 and (100 - a1 - b1 - c1) ≠ 0, a1 may be 0.

[0021] In the titanium alloy according to this embodiment, the BCC phase and the B2 phase form a coherent structure. Specifically, at least a part of the BCC phase and at least a part of the B2 phase are coherent at the interface. This interface may be formed linearly. By the BCC phase and the B2 phase forming a coherent structure, the strength of the titanium alloy, particularly the strength at high temperatures, can be improved.

[0022] The content d (vol%) of the B2 phase in the titanium alloy satisfies 30 < d < 80. Thereby, the strength of the titanium alloy can be improved. The content d of the B2 phase is determined by the area ratio from the SEM (Scanning Electron Microscope) image of the cross-section of the titanium alloy.

[0023] As an example, metal M1 may be V and metal M2 may be Ni. In this case, for the component Ti (100-a1-b1-c1) Al a1 V b1 Ni c1 the content b1 (at%) of V satisfies 10 < b1 < 40, and the content c1 (at%) of Ni in this component may satisfy 5 < c1 < 30.

[0024] As another example, metal M1 may be V and metal M2 may be Fe. In this case, for the component Ti (100-a1-b1-c1) Al a1 V b1 Fe c1 the content b1 (at%) of V satisfies 0.5 < b1 < 10, and the content c1 (at%) of Fe in this component may satisfy 15 < c1 < 50. However, b1 may satisfy 0 < b1 ≤ 0.5, and when a1 ≠ 0 and c1 ≠ 0 and (100 - a1 - b1 - c1) ≠ 0, b1 may be 0.

[0025] As another example, metal M1 may be V and metal M2 may be Co. In this case, for the component Ti (100-a1-b1-c1) Al a1 V b1 Co c1The content b1 (at%) of V in [it] satisfies 20 < b1 < 60, and the content c1 (at%) of Co in this component may satisfy 5 < c1 < 40.

[0026] As another example, metal M1 may be V and metal M2 may be Ru. In this case, the component Ti (100-a1-b1-c1) Al a1 V b1 Ru c1 The content b1 (at%) of V in [it] satisfies 0.5 < b1 < 30, and the content c1 (at%) of Ru in this component may satisfy 5 < c1 < 50. However, b1 may satisfy 0 < b1 ≦ 0.5, and when a1 ≠ 0 and c1 ≠ 0 and (100 - a1 - b1 - c1) ≠ 0, b1 may be 0.

[0027] In the case of this composition, the BCC phase may be a V-rich phase and the B2 phase may be a Ru-rich phase. Here, the X-rich phase is a phase in which the atomic ratio of element X is larger than that of other elements in a certain component. Therefore, in the V-rich phase, b1 > a1 and b1 > c1 and b1 > (100 - a1 - b1 - c1). Also, in the Ru-rich phase, c1 > a1 and c1 > b1 and c1 > (100 - a1 - b1 - c1).

[0028] (Method for manufacturing a titanium alloy) FIG. 2 is a flowchart showing the flow of a method for manufacturing a titanium alloy according to an embodiment of the present invention. The titanium alloy according to this embodiment includes a preparation step (S1), a homogenization step (S2), and a generation step (S3).

[0029] The preparation step (S1) is a step of preparing an ingot composed of a component consisting of Ti, Al, metal M1, and metal M2 and other inevitable impurities, capable of generating a B2 phase, and having a melting point Tm (K).

[0030] The components of the ingot excluding inevitable impurities are Ti (100-a2-b2-c2) Al a2 M1 b2 M2 c2It is represented by. Metal M1 is one or more elements selected from the group consisting of V, Nb, Mo, and Zr, and metal M2 is one element selected from the group consisting of Ru, Sc, Ni, Co, Rh, Pd, Pt, Au, and Ir.

[0031] The preparation process may include melting the raw materials of Ti, Al, metal M1, and metal M2 by, for example, the vacuum arc melting method, and cooling the melted alloy to obtain an ingot.

[0032] [[ID=�]] The inventors calculated the phase diagram and estimated the preferable ranges of the contents of Al, metal M1, and metal M2, and the melting point and the like. Specifically, the inventors calculated the phase diagram of the ternary system of V, metal M1, and metal M2 excluding Al using thermodynamic calculation software (ThermoCalc), estimated the phase diagram of the quaternary system with Al added based on the result, and estimated the preferable ranges of the contents of each element and the melting point and the like. Hereinafter, based on the estimation results, the preferable ranges of the contents of each element and the like will be described.

[0033] Component Ti according to the present embodiment (100-a2-b2-c2) Al a2 M1 b2 M2 c2 [[ID=㉑]] (100-a2-b2-c2) The content a2 (at%) of Al in satisfies 0.5 < a2 < 30. It is preferable that a2 satisfies a2 < 10. By a2 satisfying a2 < 10, generation of an unintended compound (for example, a V-rich BCC phase or the like) in the production process can be suppressed. However, a2 may satisfy 0 < a2 ≤ 0.5, and when b2 ≠ 0 and c2 ≠ 0 and (100 - a2 - b2 - c2) ≠ 0, a2 may be 0.

[0034] As an example, when metal M1 is V and metal M2 is Ni, component Ti (100-a2-b2-c2) Al <00000ģ0>V <00000ģ1>Ni <00000ģ2>The content b2 (at%) of V in satisfies 10 < b2 < 40, and the content c2 (at%) of Ni in this component may satisfy 5 < c2 < 30.

[0035] When b2 ≤ 10, Ti2Ni can be generated in the production process. When b2 ≥ 40, a crystal phase with a BCC structure that has poor oxidation resistance can be generated in the production process. By satisfying 10 < b2 < 40 for b2, the generation of unintended substances in the production process is suppressed.

[0036] When c2 ≤ 5, Ti2Ni can be generated in the production process. When c2 ≥ 30, Ni3V can be generated in the production process. By satisfying 5 < c2 < 30 for c2, the generation of unintended substances in the production process can be suppressed.

[0037] As another example, when metal M1 is V and metal M2 is Fe, for the component Ti (100-a2-b2-c2) Al a2 V b2 Fe c2 the content b2 (at%) of V in it may satisfy 0.5 < b2 < 10, and the content c2 (at%) of Fe in this component may satisfy 15 < c2 < 50. However, b2 may satisfy 0 < b2 ≤ 0.5, and when a2 ≠ 0 and c2 ≠ 0 and (100 - a2 - b2 - c2) ≠ 0, b2 may be 0.

[0038] When b2 ≥ 10, a Laves phase (TiFe2) can be generated in the production process. By satisfying b2 < 10 for b2, the generation of unintended substances in the production process is suppressed.

[0039] When c2 ≤ 15, the B2 phase is not generated in the production process. When c2 ≥ 50, a Laves phase can be generated in the production process. By satisfying 0.5 < b2 < 10 for b2, while suppressing the generation of unintended substances in the production process, it becomes possible to more reliably generate the B2 phase.

[0040] As another example, when metal M1 is V and metal M2 is Co, for the component Ti (100-a2-b2-c2) Al a2 V b2 Co c2The content b2 (at%) of V in it satisfies 20 < b2 < 60, and the content c2 (at%) of Co in this component may satisfy 5 < c2 < 40.

[0041] When b2 ≤ 20, Ti2Co may be generated in the production process. When b2 ≥ 60, a crystal phase with a BCC structure having poor oxidation resistance may be generated in the production process. By satisfying 20 < b2 < 60 for b2, it is possible to suppress the generation of unintended substances in the production process.

[0042] When c2 ≤ 5, the B2 phase is not generated in the production process. When c2 ≥ 40, Co2Ti may be generated in the production process. By satisfying 5 < c2 < 40 for c2, it is possible to more surely generate the B2 phase while suppressing the generation of unintended substances in the production process.

[0043] As another example, when the metal M1 is V and the metal M2 is Ru, the component Ti (100-a2-b2-c2) Al a2 V b2 Ru c2 The content b2 (at%) of V in it satisfies 0.5 < b2 < 30, and the content c2 (at%) of Ru in this component may satisfy 5 < c2 < 50. However, b2 may satisfy 0 < b2 ≤ 0.5, and when a2 ≠ 0 and c2 ≠ 0 and (100 - a2 - b2 - c2) ≠ 0, b2 may be 0. <00骑射の歴史は、中国を始めとするアジア諸国において古くから存在しており、多くの民族がそれぞれ独自の文化と技術を持ち、長い間発展してきました。

[0044] When b2 ≥ 30, a crystal phase having an HCP structure may be generated in the production process. By satisfying b2 < 30 for b骑射の歴史は、中国を始めとするアジア諸国において古くから存在しており、多くの民族がそれぞれ独自の文化と技術を持ち、長い間発展してきました。2, it is possible to suppress the generation of unintended substances in the production process.

[0045] When c2 ≤ 5, the B2 phase is not generated in the production process. When c2 ≥ 50, a crystal phase having a BCC structure with poor oxidation resistance may be generated in the production process. By satisfying 5 < c骑射の歴史は、中国を始めとするアジア諸国において古くから存在しており、多くの民族がそれぞれ独自の文化と技術を持ち、長い間発展してきました。2 < 50 for c2, it is possible to more surely generate the B2 phase while suppressing the generation of unintended substances in the production process.

[0046] The homogenization process (S2) is a process of homogenizing an ingot by holding the ingot at a first heat treatment temperature T1 (K) that satisfies Tm - 300 < T1 < Tm for 0.5 hours or more to obtain a homogenized ingot having a BCC structure. By satisfying Tm - 300 < T1 < Tm for the first heat treatment temperature T1, it becomes possible to homogenize the ingot while suppressing melting of the ingot. The first heat treatment temperature T1 may be, for example, 1400 < T1 < 1900.

[0047] Specifically, the homogenization process may include holding the ingot at the first heat treatment temperature T1 for 0.5 hours or more and cooling the ingot to room temperature to obtain a homogenized ingot. The cooling rate may be, for example, -1 °C / second to -400 °C / second. The ingot is preferably quenched from the first heat treatment temperature T1 to room temperature, for example, by water cooling. By quenching the ingot, it is possible to suppress an unintended heat treatment from being performed during cooling of the ingot.

[0048] The time for holding the ingot at the first heat treatment temperature T1 may be appropriately adjusted according to components excluding inevitable impurities of the ingot and the first heat treatment temperature T1, etc., and may be, for example, about 5 hours.

[0049] When the component excluding the inevitable impurities of the ingot is Ti (100-a2-b2-c2) Al a2 V b2 Ru c2 and has a composition of, the melting point of the ingot is 1900 - 2000 K. Therefore, in the case of this composition, it is preferable that the first heat treatment temperature T1 (K) is 1700 < T1 < 1900.

[0050] The forming process (S3) is a process of holding the ingot homogenized in the homogenization process (S2) at the second heat treatment temperature T2 for 0.1 hours or more to form a crystal phase having a B2 structure. The time for holding the homogenized ingot at the second heat treatment temperature T2 may be appropriately adjusted according to the components excluding the inevitable impurities of the ingot and the second heat treatment temperature T2, etc. The time for holding the ingot at the second heat treatment temperature T2 may be, for example, about 2 hours or about 24 hours.

[0051] When the component excluding the inevitable impurities of the ingot is Ti (100-a2-b2-c2) Al a2 V b2 Ru c2 When having the composition of, the second heat treatment temperature T2 (K) may satisfy 673 < T2 < 1523. Thereby, it becomes possible to more reliably form the B2 phase.

[0052] Also, in the components Ti (100-a2-b2-c2) Al a2 M1 b2 M2 c2 When the metal M1 is V and the metal M2 is Fe, Co, or Ni, the second heat treatment temperature T2 may be 673 < T2 < 1273.

[0053] (Example) Hereinafter, the titanium alloy and its manufacturing method will be described more specifically using examples. However, the descriptions of the raw materials, manufacturing methods, compositions of the titanium alloys, etc. below do not limit any embodiments of the titanium alloy and its manufacturing method according to the present invention.

[0054] In the example, a titanium alloy composed of the components of Ti 25 Al 25 V 25 Ru 25 and inevitable impurities was produced.

[0055] First, Ti 25 Al 25 V 25 Ru 25The raw materials for the composition shown above were weighed out: Ti (Furuuchi Chemical Co., Ltd., purity 99.9%, stick 1φ×10mm L), Al (Furuuchi Chemical Co., Ltd., purity 99.999%, shot), V (Furuuchi Chemical Co., Ltd., purity 99.9%, chunk), and Ru (Furuya Metal Co., Ltd., purity 99.99%, powder).

[0056] The weighed raw materials were melted by arc melting to produce 20 g alloy ingots. Two 1 mm thick plates were cut from each ingot. -3 The plate was held at the first heat treatment temperature of 1773 K in a vacuum of 100 Pa for 5 hours to undergo homogenization treatment, and then cooled in the furnace.

[0057] The homogenized plate, 1 mm thick, was cut into approximately three equal pieces, and the pieces were sealed in quartz tubes in an Ar gas atmosphere. Then, heat treatment was performed at the second heat treatment temperature and for the heat treatment time shown below, followed by water cooling to obtain titanium alloy samples 1 to 5. Sample name: Second heat treatment temperature: Heat treatment time Sample 1: 1523K: 2 hours Sample 2: 1273K: 2 hours Sample 3: 1173K: 24 hours Sample 4: 1073K: 24 hours Sample 5: 973K: 24 hours

[0058] The microstructure of the plate and each of Samples 1 to 5 immediately after homogenization was observed using an electron reflection detector in a SEM (JEOL Ltd., JSM-7900F) and a Transmission Electron Microscope (TEM) (JEOL Ltd., 2100F). The crystalline phases of each sample were identified by XRD measurement using an X-ray diffraction (XRD) device (Rigaku Corporation, Smart Lab) and elemental analysis using EDX (Energy Dispersive X-ray Spectroscopy). The Vickers hardness of each of Samples 1 to 5 was also measured using a hardness tester.

[0059] Figure 3 shows an SEM image of the homogenized plate. XRD measurement and EDX elemental analysis revealed that a homogenous single BCC phase was produced.

[0060] Figure 4 shows an SEM image of Sample 1. In Figure 4, the black area represents the BCC phase, and the gray area represents the B2 phase. The interface between the BCC and B2 phases is linear, suggesting that the BCC and B2 phases are coherent. This structure, in which the BCC and B2 phases are coherent, is advantageous for improving mechanical properties. Furthermore, in Sample 1, the B2 phase is partially coarsened compared to Samples 2 and 3, suggesting that the precipitated B2 phase has begun to dissolve into the BCC phase. Therefore, if the second heat treatment temperature is higher than 1523 K, the B2 phase may not be generated.

[0061] Figure 5 is an SEM image of sample 2, and Figure 6 is an SEM image of sample 3. As shown in Figures 5 and 6, the BCC and B2 phases with a linear interface were observed in samples 2 and 3, suggesting that a structure in which the BCC and B2 phases are coherent was formed. In samples 2 and 3, cubic B2 phases were formed.

[0062] The structure of Sample 3 in this example is not seen in titanium 64 alloy (Ti-6Al-4V). 25 Al 25 V 25 Ru 25 However, in this sample, a structure in which the B2 phase and the BCC phase are coherent, as in the examples of the present application, is not formed. This is presumably because the heat treatment temperature was lower than in the examples of the present application, and the elements were not sufficiently diffused.

[0063] Figure 7 is a further enlarged TEM image of Sample 2. Elemental analysis of Sample 2 using EDX revealed that the white regions were Ru-rich B2 phases with Ti 27.2 at%, Al 13.6 at%, V 6.6 at%, and Ru 52.6 at%. The black regions were V-rich BCC phases with Ti 11.3 at%, Al 17.5 at%, V 52.7 at%, and Ru 18.5 at%. Thus, in Sample 2, the majority of the total V was contained in the B2 phase.

[0064] 8 and 9 are SEM images of Sample 4 and Sample 5, respectively. In Figures 8 and 9, the interface between the BCC phase and the B2 phase, as seen in Samples 1 to 3, is not visible. However, it is thought that in Samples 4 and 5, these crystalline phases are refined and cannot be detected in the SEM images.

[0065] Fig. 10 shows the XRD pattern of sample 2. As shown in Fig. 10, a peak of the B2 phase was observed. Furthermore, as described above, a BCC phase was also generated in sample 2, but the peak of only the B2 phase was observed. This suggests that the lattice constants of the B2 phase and the BCC phase are very similar. Therefore, it is thought that the B2 phase and the BCC phase easily form a coherent structure.

[0066] FIG. 11 shows the results of measuring the Vickers hardness of Samples 1 to 5 at room temperature (25°C). The Vickers hardness of Sample 1 is 840 HV. The Vickers hardness of the plate after the homogenization treatment is 800 HV, which indicates that the Vickers hardness is improved by the formation of the B2 phase. As shown in FIG. 11, the Vickers hardness increases as the second heat treatment temperature decreases, and the Vickers hardness of Samples 4 and 5 is particularly high. This is presumably because the microstructure is finer than that of the other samples.

[0067] The present invention has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the components and treatment processes, and that such modifications are also within the scope of the present invention.

Claims

1. a preparation step of preparing an ingot that is composed of Ti, Al, metal M1, metal M2, and other inevitable impurities, that can generate a crystalline phase having a B2 structure, and that has a melting point Tm (K); a homogenization step of homogenizing the ingot by holding the ingot at a first heat treatment temperature T1 (K) that satisfies Tm-300<T1<Tm for 0.5 hours or more to obtain a homogenized ingot having a BCC structure; and a generating step of holding the ingot homogenized in the homogenizing step at a second heat treatment temperature T2 (K) for 0.1 hours or more to generate a crystalline phase having a B2 structure, The content a (at%) of Al in the component satisfies 0.5<a<30, The metal M1 is one or more elements selected from the group consisting of V, Nb, Mo, and Zr, The metal M2 is one element selected from the group consisting of Ru, Sc, Ni, Co, Rh, Pd, Pt, Au, and Ir. Titanium alloy manufacturing method.

2. The metal M1 is V, The metal M2 is Ni, the content b (at%) of V in the component satisfies 10<b<40, The content c (at%) of Ni in the components satisfies 5<c<30. A method for producing the titanium alloy according to claim 1.

3. The metal M1 is V, The metal M2 is Fe, the content b (at%) of V in the component satisfies 0.5<b<10, The content c (at%) of Fe in the components satisfies 15<c<50. A method for producing the titanium alloy according to claim 1.

4. The metal M1 is V, The metal M2 is Co, the content b (at%) of V in the component satisfies 20<b<60, The content c (at%) of Co in the components satisfies 5<c<40. A method for producing the titanium alloy according to claim 1.

5. The metal M1 is V, the metal M2 is Ru, the content b (at%) of V in the component satisfies 0.5<b<30, The content c (at%) of Ru in the components satisfies 5<c<50. A method for producing the titanium alloy according to claim 1.

6. the first heat treatment temperature T1 satisfies 1700<T1<1900; The method for producing the titanium alloy according to claim 5.

7. the second heat treatment temperature T2 satisfies 673<T2<1523; The method for producing the titanium alloy according to claim 5.

8. The homogenizing step includes holding the ingot at the first heat treatment temperature T1 for 0.5 hours or more and water-cooling the ingot to room temperature to obtain the homogenized ingot. A method for producing the titanium alloy according to claim 1.

9. The preparing step includes melting raw materials of Al, metal M1, metal M2, and Ti, and cooling the molten alloy to obtain the ingot. A method for producing the titanium alloy according to claim 1.

10. A titanium alloy, consisting of Ti, Al, metal M1 and metal M2, and other inevitable impurities; It has a BCC phase, which is a crystalline phase having a BCC structure, and a B2 phase, which is a crystalline phase having a B2 structure, The content a (at%) of Al in the component satisfies 0.5<a<30, The metal M1 is one or more elements selected from the group consisting of V, Nb, Mo, and Zr, The metal M2 is one element selected from the group consisting of Ru, Sc, Ni, Co, Rh, Pd, Pt, Au, and Ir, the BCC phase and the B2 phase form a coherent structure; The content d (vol%) of the B2 phase in the titanium alloy satisfies 30<d<80. Titanium alloy.

11. The metal M1 is V, The metal M2 is Ni, the content b (at%) of V in the component satisfies 10<b<40, The content c (at%) of Ni in the components satisfies 5<c<30. The titanium alloy of claim 10.

12. The metal M1 is V, The metal M2 is Fe, the content b (at%) of V in the component satisfies 0.5<b<10, The content c (at%) of Fe in the components satisfies 15<c<50. The titanium alloy of claim 10.

13. The metal M1 is V, The metal M2 is Co, the content b (at%) of V in the component satisfies 20<b<60, The content c (at%) of Co in the components satisfies 5<c<40. The titanium alloy of claim 10.

14. The metal M1 is V, the metal M2 is Ru, the content b (at%) of V in the component satisfies 0.5<b<30, The content c (at%) of Ru in the components satisfies 5<c<50. The titanium alloy of claim 10.

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