Preparation process of powder metallurgy titanium alloy

Abstract

The invention relates to the technical field of powder metallurgy titanium, and particularly discloses a preparation process of a powder metallurgy titanium alloy. A preparation technology of a powder metallurgy titanium alloy comprises the following steps that 200-240 parts by weight of titanium composite powder, 15-20 parts by weight of aluminum powder, 10-15 parts by weight of molybdenum powder, 8-14 parts by weight of an auxiliary agent, 5-9 parts by weight of an auxiliary agent and 1-3 parts by weight of a binding agent are taken; the titanium composite powder, the aluminum powder, the molybdenum powder, the auxiliary agent, the auxiliary agent and the binding agent are extruded, dried, smashed and sieved, then cold isostatic pressing forming treatment is conducted, then hot isostatic pressing sintering and heat treatment are conducted in sequence, and the composite material is obtained. Wherein the titanium composite powder is formed by forming a TiC and zirconium-containing composite coating layer on the surface of titanium powder through a fluidized bed chemical vapor deposition method. The preparation process of the powder metallurgy titanium alloy can be used for preparing the titanium alloy with high strength and excellent plasticity, and has the advantages of being high in machining efficiency, low in cost, free of segregation and the like.

Description

Technical Field

[0001] The present application relates to the technical field of powder metallurgy titanium, and more specifically, to a preparation process of powder metallurgy titanium alloy. Background Art

[0002] Titanium alloys are important in many fields due to their unique physical and chemical properties, such as low density, high specific strength, excellent corrosion resistance, high temperature mechanical properties, fatigue resistance and creep resistance. In particular, they have broad application prospects in aerospace, military equipment, automobile manufacturing, chemical and energy industries, and biomedical fields.

[0003] The traditional preparation method of titanium and titanium alloys is mainly through common plastic processing methods such as casting. Casting easily causes defects such as component segregation, looseness, shrinkage, etc. of the material, which limits the preparation of high-performance titanium alloys. Titanium and titanium alloys have low room temperature plasticity, low deformation limit, high deformation resistance, and are prone to cracking when formed at room temperature. Therefore, most titanium alloys still need to be plastically formed at high temperatures, but this also greatly increases the processing cost of titanium alloys.

[0004] Powder metallurgy is an industrial technology that uses forming and sintering processes to make metal powder (or a mixture of metal powder and non-metal powder) into metal materials, high-performance non-equilibrium materials and other products. It has excellent properties such as easy forming, high processing efficiency, low cost and no segregation, and is a key technology to promote the development of new materials. Titanium alloy products prepared by powder metallurgy have high density, low oxygen, uniform structure, high strength, high toughness and other excellent properties, and low production cost, which makes up for the defects of traditional preparation methods.

[0005] With regard to the above-mentioned related technologies, the inventors found that the difficulty in the current preparation of powder metallurgy titanium alloys lies in how to achieve low oxygen content control. Appropriate oxygen content can increase the tensile strength of titanium alloys by 50-60MPa, but when its oxygen content exceeds 0.32wt%, the plasticity drops sharply and turns into brittle fracture, which greatly hinders the application and development of powder metallurgy titanium alloys. Summary of the invention

[0006] In order to improve the plasticity of powder metallurgy titanium alloy and obtain a powder metallurgy titanium alloy with better comprehensive performance, the present application provides a preparation process of a powder metallurgy titanium alloy.

[0007] In a first aspect, the present application provides a preparation process of a powder metallurgy titanium alloy, which adopts the following technical solution: A preparation process of a powder metallurgy titanium alloy comprises the following steps: The titanium composite powder is prepared by fluidized bed chemical vapor deposition method, zirconium chloride is placed in the gasification section, titanium powder is placed in the fluidized bed reaction section, argon gas is introduced into the system to remove the air in the entire system, and the mass ratio of titanium powder to zirconium chloride is 1: (0.5-0.8); The gasification section is heated to 230-330°C, the fluidized bed reaction section is heated to 550-650°C, argon is continuously introduced into the gasification section and the fluidized bed reaction section, H2 and CH4 are introduced into the fluidized bed reaction section at flow rates of 100-200 mL / min and 200-300 mL / min, respectively, the reaction is continued for 1-1.5 h, H2 and CH4 are shut off, and the mixture is cooled to room temperature in an argon atmosphere to obtain a titanium composite powder; By weight, take 200-240 parts of titanium composite powder, 15-20 parts of aluminum powder, 10-15 parts of molybdenum powder, 8-14 parts of additives, 5-9 parts of auxiliary agents, and 1-3 parts of binder; The titanium composite powder, aluminum powder, molybdenum powder, additives, auxiliary agents and binders are extruded, dried, crushed, sieved, and then subjected to cold isostatic pressing to obtain a blank; The blank is subjected to hot isostatic sintering and heat treatment in sequence to obtain the product.

[0008] By adopting the above technical solution, methane as a gaseous carbon source can contact and react with titanium atoms on the surface of titanium powder in the reaction section to generate TiC. As the reaction proceeds, TiC is deposited on the surface of titanium powder to form a TiC-containing coating layer. Zirconium chloride undergoes a reduction reaction in the gas atmosphere of methane and hydrogen, and a zirconium-containing coating layer is uniformly formed on the surface of titanium powder, which can form a physical barrier, effectively preventing a large amount of titanium powder from being over-oxidized during subsequent processing, and effectively controlling the oxygen content of powder metallurgy titanium alloy. The fluidized bed chemical vapor deposition method is adopted, combining the advantages of vapor deposition and fluidized bed technology, to form a uniform TiC and zirconium-containing composite coating layer on the surface of titanium powder to form a titanium composite powder.

[0009] TiC and zirconium-containing compounds form a composite coating on the surface of titanium powder, which has good interface bonding with the titanium matrix and can form a dense interface structure or solid solution, effectively reducing defects such as pores and cracks at the interface, which helps to transfer loads during plastic deformation and avoid local stress concentration. This dense interface bonding can significantly reduce the porosity of powder metallurgy titanium alloys, improve the overall density of titanium alloys, and then improve the plasticity and strength of titanium alloys, so that titanium alloys can better resist deformation and fracture when subjected to stress.

[0010] Because TiC has high hardness and high strength, it can serve as a barrier to crack propagation. When the crack propagates to the TiC coating, its high hardness and high strength characteristics will force the crack to change direction or stop propagating, thereby improving the fracture toughness of the material.

[0011] The TiC coating can act as a nucleation point during the sintering process, promoting the refinement of titanium alloy grains and preventing the appearance of large pores. Refined grains help reduce stress concentration and improve the plastic deformation capacity of the material. The zirconium coating can further refine the grains, reduce grain boundary defects, and further enhance the plasticity and toughness of the material. The zirconium coating can improve the thermal stability of powder metallurgy titanium alloys, reduce softening and degradation when used at high temperatures, and help maintain the plasticity of the alloy.

[0012] Optionally, the molding pressure of the cold isostatic pressing process is 300-500 MPa, and the holding time is 30-50 min.

[0013] By adopting the above technical scheme, the molding pressure of the cold isostatic pressing process is set within the range of 300-500MPa, which ensures the density and uniformity of the blank, and is beneficial to improving the performance of the final product. The holding time is set to 30-50min, which not only ensures sufficient molding time, but also avoids energy waste caused by too long time, thereby improving production efficiency.

[0014] Optionally, the protective atmosphere for hot isostatic sintering is argon, the sintering temperature is 850-950° C., the holding time is 1-2 h, and the holding pressure is 200-300 MPa.

[0015] By adopting the above technical solution, hot isostatic sintering is carried out under argon protection, which effectively prevents oxidation, ensures quality stability during the sintering process, prevents the increase of oxygen content in the titanium alloy, and accurately controls the sintering temperature, holding time and holding pressure, which helps to obtain titanium alloy materials with excellent performance.

[0016] Optionally, the heat treatment specifically includes the following steps: At vacuum degree ≤10 -2 Under the condition of Pa, the hot isostatic sintering blank is first heated to 950-990°C at 10°C / min, kept warm for 2-4h, then furnace cooled to 500-600°C, kept warm for 1-1.5h, and finally air cooled to room temperature.

[0017] By adopting the above technical solution, the microstructure and phase change process of the material are effectively controlled through staged heating, insulation and cooling under vacuum conditions, thereby preventing the occurrence of large pores and gaps, improving the density of the titanium alloy, reducing oxidation and contamination on the surface of the material, and preventing the increase of oxygen content in the titanium alloy.

[0018] Optionally, the flow rates of the inert gas in the gasification section and the fluidized bed reaction section are 400-500 mL / min and 1000-1100 mL / min, respectively.

[0019] By adopting the above technical solution and controlling the flow rate of the inert gas, the gas fluidity and mass transfer efficiency in the fluidized bed are enhanced, which is beneficial to the full contact and reaction between the reactants and improves the coverage rate and coating effect of the titanium powder.

[0020] Optionally, the auxiliary agent is selected from any one of lithium carbonate or lithium chloride.

[0021] By adopting the above technical solution, lithium is an active element that can react with oxygen to form oxides or salts, thereby removing dissolved oxygen from the titanium alloy, reducing oxide inclusions, and improving the plasticity of the alloy.

[0022] Optionally, the auxiliary agent is polyethylene glycol.

[0023] By adopting the above technical solution, the addition of polyethylene glycol can reduce the friction coefficient between powder particles, improve the fluidity of powder, help to disperse different powders more evenly, prevent powder agglomeration, and improve the smoothness of powder pressing. In addition, polyethylene glycol can fill the pores between powders, further reduce the porosity of titanium alloy, and improve the density inside titanium alloy, thereby helping to improve the plasticity of titanium alloy.

[0024] Optionally, the adhesive is selected from any one of a polyurethane adhesive or an acrylate adhesive.

[0025] By adopting the above technical solution, the addition of polyurethane and acrylate binders can, on the one hand, interact with the surface of titanium alloy powder particles to increase the bonding force between powders, thereby improving the strength and plasticity of the green billet.

[0026] In a second aspect, the present application provides a powder metallurgy titanium alloy prepared by a powder metallurgy titanium alloy preparation process of the present application.

[0027] By adopting the above technical solution, the powder metallurgy titanium alloy prepared by the preparation process of the present application can have an oxygen content controlled within 0.32wt%, has good plasticity and ductility, excellent performance, and has good application and development prospects.

[0028] In summary, this application has the following beneficial effects: 1. Since the present application adopts fluidized bed chemical vapor deposition method, a uniform composite coating layer of TiC and zirconium elements is formed on the surface of titanium powder, and a dense interface structure or solid solution is formed between the titanium matrix and the coating, which effectively reduces defects such as pores and cracks at the interface, promotes the transfer of loads during plastic deformation of powder metallurgy titanium alloy, avoids local stress concentration, and significantly improves the plasticity and strength of powder metallurgy titanium alloy.

[0029] 2. The composite coating layer of TiC and zirconium-containing elements can enhance the bonding force between powder particles, promote the bonding between powder particles, reduce the porosity in the sintered body, and improve the density of powder metallurgy titanium alloy, thereby improving the plasticity of powder metallurgy titanium alloy.

[0030] 3. The preparation process of the present application can control the oxygen content of the powder metallurgy titanium alloy within 0.32wt%, so that the titanium alloy has excellent tensile strength while having good plasticity and ductility. DETAILED DESCRIPTION

[0031] The following examples further illustrate the present application in detail.

[0032] raw material Unless otherwise specified, the raw materials used in the preparation examples, embodiments and comparative examples in this application are all commercially available products, specifically: Titanium powder, purity>99.9%, particle size 800-1000nm; Zirconium chloride, selected from Shanghai Jizhi Biochemical Technology Co., Ltd., Z53080; Aluminum powder, purity>99.9%, particle size 1-30μm; Molybdenum powder, purity> 99.9%, particle size 15-45μm; TiC, selected from Shanghai Jizhi Biochemical Technology Co., Ltd., T96680; Lithium carbonate, selected from Juepai Chemical, JC-0035; Lithium chloride, selected from Juepai Chemical, JZ-0001; Polyethylene glycol, selected from Jincheng Chemical, PEG-1000; Polyurethane adhesive, selected from Anda Huatai New Materials, AH-1704B-2; Acrylic adhesive, selected from Shangjin Chengzhan New Materials, SGR-5117.

[0033] Preparation example of titanium composite powder Preparation Example 1 The titanium composite powder, the raw materials include titanium powder and zirconium chloride in a mass ratio of 1:0.8, and the preparation method thereof includes the following steps: S1: Use deionized water to perform ultrasonic cleaning pretreatment on titanium powder to remove surface impurities and oil stains, and then dry and sieve it for use; S2: Use a fluidized bed chemical vapor deposition device, which includes a fluidized bed reactor and a gasifier. Place zirconium chloride in the gasification section and titanium powder in the fluidized bed reaction section. Pass excess argon into the gasification section to remove air from the entire system. S3: Heat the gasification section to 300°C and the fluidized bed reaction section to 470°C at a heating rate of 10°C / min. S4: Continue to pass argon into the gasification section at a flow rate of 450mL / min, and continue to pass argon into the fluidized bed reaction section at a flow rate of 1000mL / min. Pass H2 and CH4 into the fluidized bed reaction section at flow rates of 200mL / min and 270mL / min, respectively. Continue the reaction for 1.2h, shut down H2 and CH4, and cool to room temperature in an argon atmosphere to obtain the product.

[0034] Preparation Example 2 Titanium composite powder, the raw materials include titanium powder and zirconium chloride in a mass ratio of 1:0.5, and the preparation method thereof includes the following steps: S1: Use deionized water to perform ultrasonic cleaning pretreatment on titanium powder to remove surface impurities and oil stains, and then dry and sieve it for use; S2: Use a fluidized bed chemical vapor deposition device, which includes a fluidized bed reactor and a gasifier. Place zirconium chloride in the gasification section and titanium powder in the fluidized bed reaction section. Pass excess argon into the gasification section to remove air from the entire system. S3: Heat the gasification section to 270°C and the fluidized bed reaction section to 620°C at a heating rate of 10°C / min. S4: Continue to pass argon into the gasification section at a flow rate of 400mL / min, and continue to pass argon into the fluidized bed reaction section at a flow rate of 1050mL / min. Pass H2 and CH4 into the fluidized bed reaction section at flow rates of 100mL / min and 200mL / min, respectively. Continue the reaction for 1h, shut down H2 and CH4, and cool to room temperature in an argon atmosphere to obtain the product.

[0035] Preparation Example 3 Titanium composite powder, the raw materials include titanium powder and zirconium chloride in a mass ratio of 1:0.6, and the preparation method thereof includes the following steps: S1: Use deionized water to perform ultrasonic cleaning pretreatment on titanium powder to remove surface impurities and oil stains, and then dry and sieve it for use; S2: Use a fluidized bed chemical vapor deposition device, which includes a fluidized bed reactor and a gasifier. Place zirconium chloride in the gasification section and titanium powder in the fluidized bed reaction section. Pass excess argon into the gasification section to remove air in the entire system. S3: Heat the gasification section to 230°C and the fluidized bed reaction section to 550°C at a heating rate of 10°C / min. S4: Continue to pass argon into the gasification section at a flow rate of 450mL / min, and continue to pass argon into the fluidized bed reaction section at a flow rate of 1000mL / min. Pass H2 and CH4 into the fluidized bed reaction section at flow rates of 150mL / min and 220mL / min, respectively. Continue the reaction for 1h, shut down H2 and CH4, and cool to room temperature in an argon atmosphere to obtain the product.

[0036] Preparation Example 4 The titanium composite powder, the raw materials include titanium powder and zirconium chloride in a mass ratio of 1:0.8, and the preparation method thereof includes the following steps: S1: Use deionized water to perform ultrasonic cleaning pretreatment on titanium powder to remove surface impurities and oil stains, and then dry and sieve it for use; S2: using a fluidized bed chemical vapor deposition device, the device includes a fluidized bed reactor and a gasifier, placing zirconium chloride in the gasification section, placing titanium powder in the fluidized bed reaction section, and introducing excess argon gas into the gasification section to remove air in the entire system; S3: At a heating rate of 10°C / min, the gasification section is heated to 230-330°C, and the fluidized bed reaction section is heated to 550-650°C; S4: Continue to introduce argon into the gasification section at a flow rate of 400-500mL / min, and continue to introduce argon into the fluidized bed reaction section at a flow rate of 1000-1100mL / min; introduce H2 and CH4 into the fluidized bed reaction section at a flow rate of 100-200mL / min and 200-300mL / min, and continue the reaction for 1-1.5h, shut off H2 and CH4, and cool to room temperature in an argon atmosphere to obtain.

[0037] Preparation Example 5 Titanium composite powder, the raw materials include titanium powder and zirconium chloride in a mass ratio of 1:0.7, and the preparation method thereof includes the following steps: S1: Use deionized water to perform ultrasonic cleaning pretreatment on titanium powder to remove surface impurities and oil stains, and then dry and sieve it for use; S2: using a fluidized bed chemical vapor deposition device, the device includes a fluidized bed reactor and a gasifier, placing zirconium chloride in the gasification section, placing titanium powder in the fluidized bed reaction section, and introducing excess argon gas into the gasification section to remove air in the entire system; S3: at a heating rate of 10°C / min, the gasification section is heated to 330°C and the fluidized bed reaction section is heated to 650°C; S4: Continue to introduce argon into the gasification section at a flow rate of 500 mL / min, and continue to introduce argon into the fluidized bed reaction section at a flow rate of 1050 mL / min; introduce H2 and CH4 into the fluidized bed reaction section at a flow rate of 170 mL / min and 250 mL / min, and continue the reaction for 1.3 h, shut off H2 and CH4, and cool to room temperature in an argon atmosphere.

[0038] Preparation Example 6 The titanium composite powder is different from that in Preparation Example 1 in that its preparation method comprises the following steps: S1: Use deionized water to perform ultrasonic cleaning pretreatment on titanium powder to remove surface impurities and oil stains, and then dry and sieve it for use; S2: using a fluidized bed chemical vapor deposition device, the device includes a fluidized bed reactor and a gasifier, placing zirconium chloride in the gasification section, placing titanium powder in the fluidized bed reaction section, and introducing excess argon gas into the gasification section to remove air in the entire system; S3: Raise the temperature of the gasification section to 300°C and the temperature of the fluidized bed reaction section to 470°C at a heating rate of 10°C / min; S4: Continue to introduce argon into the gasification section at a flow rate of 450 mL / min, and continue to introduce argon into the fluidized bed reaction section at a flow rate of 1000 mL / min; introduce H2 into the fluidized bed reaction section at a flow rate of 300 mL / min, continue the reaction for 1.2 h, turn off H2, and cool to room temperature in an argon atmosphere to obtain. Example

[0039] Example 1 A powder metallurgy titanium alloy, the raw materials and amounts are shown in Table 1, wherein the titanium composite powder is obtained from Preparation Example 1, the auxiliary agent is lithium carbonate, the auxiliary agent is polyethylene glycol, and the binder is a polyurethane binder.

[0040] Table 1 Example 1 Example 2 Example 3 Example 4 Titanium composite powder / Kg 220 200 230 240 Aluminum powder / Kg 17 20 15 18 Molybdenum powder / Kg 12 10 13 15 Additives / Kg 11 8 10 14 Auxiliary agent / Kg 7 9 6 5 Binder / Kg 3 1 2 3 The preparation process of the above powder metallurgy titanium alloy comprises the following steps: S1: Put titanium composite powder, aluminum powder, molybdenum powder, additives, auxiliary agents and binders into an extruder for extrusion, drying, crushing and sieving, and then put them into a cold isostatic pressing sleeve, set the cold isostatic pressing pressure to 500MPa, and the holding time to 40min, and perform cold isostatic pressing to obtain a blank; S2: placing the blank into a hot isostatic press and performing hot isostatic sintering treatment under the protection of argon gas, with a sintering temperature of 850°C, a holding time of 2h, and a holding pressure of 300MPa; S3: In the vacuum heat treatment furnace, set the vacuum degree ≤ 10 -2 Pa, the sintered billet is heat treated, first the billet that has undergone hot isostatic sintering is heated to 950°C at a rate of 10°C / min, kept warm for 4h, then furnace cooled to 500°C, kept warm for 1h, and finally air cooled to room temperature.

[0041] Example 2 A powder metallurgy titanium alloy, which is different from Example 1 in that the raw materials and amounts are as shown in Table 1, wherein the auxiliary agent is lithium chloride, and the binder is an acrylate binder; The preparation process of the above powder metallurgy titanium alloy comprises the following steps: S1: Put titanium composite powder, aluminum powder, molybdenum powder, additives, auxiliary agents and binders into an extruder for extrusion, drying, crushing and sieving, and then put them into a cold isostatic pressing sleeve, set the cold isostatic pressing pressure to 400MPa, and hold the pressure for 30min, and perform cold isostatic pressing to obtain a blank; S2: placing the blank into a hot isostatic press and performing hot isostatic sintering treatment under the protection of argon gas, with a sintering temperature of 950°C, a holding time of 1h, and a holding pressure of 250MPa; S3: In the vacuum heat treatment furnace, set the vacuum degree ≤ 10 -2 Pa, the sintered billet is heat treated, first the billet that has been hot isostatically sintered is heated to 970°C at a rate of 10°C / min, kept warm for 3h, then furnace cooled to 550°C, kept warm for 1.2h, and finally air cooled to room temperature.

[0042] Example 3 A powder metallurgy titanium alloy, which is different from Example 1 in that the raw materials and amounts are as shown in Table 1, and the preparation process thereof comprises the following steps: S1: Put titanium composite powder, aluminum powder, molybdenum powder, additives, auxiliary agents and binders into an extruder for extrusion, drying, crushing and sieving, and then put them into a cold isostatic pressing sleeve, set the cold isostatic pressing pressure to 300MPa, and the holding time to 50min, and perform cold isostatic pressing to obtain a blank; S2: placing the blank into a hot isostatic press and performing hot isostatic sintering treatment under the protection of argon gas, with a sintering temperature of 900°C, a holding time of 2h, and a holding pressure of 200MPa; S3: In the vacuum heat treatment furnace, set the vacuum degree ≤ 10 -2 Pa, the sintered billet is heat treated, first the billet that has been hot isostatic sintering is heated to 990°C at a rate of 10°C / min, kept warm for 2h, then furnace cooled to 600°C, kept warm for 1.5h, and finally air cooled to room temperature.

[0043] Example 4 A powder metallurgy titanium alloy, which is different from Example 1 in that the raw materials and amounts are as shown in Table 1, and the other steps are the same as Example 1.

[0044] Example 5 A powder metallurgy titanium alloy is different from Example 1 in that the titanium composite powder in the raw material is obtained from Preparation Example 2, and the other steps are the same as Example 1.

[0045] Example 6 A powder metallurgy titanium alloy is different from Example 1 in that the titanium composite powder in the raw material is obtained from Preparation Example 3, and the other steps are the same as Example 1.

[0046] Example 7 A powder metallurgy titanium alloy is different from Example 1 in that the titanium composite powder in the raw material is obtained from Preparation Example 4, and the other steps are the same as Example 1.

[0047] Example 8 A powder metallurgy titanium alloy is different from Example 1 in that the titanium composite powder in the raw material is obtained from Preparation Example 5, and the other steps are the same as Example 1.

[0048] Comparative Example Comparative Example 1 A powder metallurgy titanium alloy is different from Example 1 in that the titanium composite powder in the raw material is obtained from Preparation Example 6, and the other steps are the same as Example 1.

[0049] Comparative Example 2 A powder metallurgy titanium alloy, which differs from Example 1 in that the titanium composite powder in the raw material is replaced by titanium powder of equal mass, and the other steps are the same as Example 1.

[0050] Comparative Example 3 A powder metallurgy titanium alloy, which differs from Example 1 in that the titanium composite powder in the raw material is replaced by titanium powder, TiC and zirconium powder in a mass ratio of 8:1.2:0.6, the total mass of the titanium powder, TiC and zirconium powder is the same as the total mass of the titanium composite powder in the raw material of Example 1, and the other steps are the same as Example 1.

[0051] Performance testing The oxygen content, tensile strength and yield strength of Examples 1-8 and Comparative Examples 1-3 were tested, and the elongation was calculated. Each group of experiments was performed 3 times, and the average value was taken as the final result and recorded in Table 2. The relevant testing methods and standards are as follows: 1. Oxygen content: Refer to GB / T 5158.1-2011 "Determination of oxygen content by metal powder reduction method Part 1: General principles" to determine the oxygen content of powder metallurgy titanium alloy; 2. Tensile strength and yield strength: Refer to GB / T 228.1-2010 "Tensile test of metallic materials Part 1: Room temperature test method" to determine the room temperature tensile strength and yield strength of powder metallurgy titanium alloy.

[0052] Table 2 Oxygen content (wt.%) Tensile strength(MPa) Yield strength(MPa) Elongation(%) Example 1 0.13±0.02 1031 948 13.8 Example 2 0.13±0.02 1022 934 12.6 Example 3 0.13±0.02 1017 921 13.4 Example 4 0.13±0.02 1025 930 14.5 Example 5 0.13±0.02 1028 939 13.7 Example 6 0.13±0.02 1029 941 13.3 Example 7 0.13±0.02 1019 928 13.4 Example 8 0.13±0.02 1024 939 12.7 Comparative Example 1 0.24±0.02 955 887 10.1 Comparative Example 2 0.31±0.02 928 855 6.2 Comparative Example 3 0.32±0.02 939 860 7.5 According to the performance test results in Table 2, it can be seen that a powder metallurgy titanium alloy preparation process of the present application is capable of preparing a titanium alloy with low oxygen content (oxygen content <0.14wt.%) and high elongation (>12%), and the titanium alloy prepared by the preparation process of the present application has high strength and high toughness mechanical properties.

[0053] Compared with the traditional powder metallurgy method of sintering and other treatments by adding additives and mixing, the fluidized bed chemical vapor deposition method forms a composite coating of TiC and zirconium elements on the surface of the titanium powder, forming a physical barrier that can effectively protect a large amount of titanium powder and prevent the titanium powder from reacting with oxygen during subsequent sintering and treatment, thereby increasing the oxygen content of the powder metallurgy titanium alloy.

[0054] Compared with a single coating layer, the composite coating layer of TiC and zirconium elements can form a denser interface structure with the titanium matrix, improve the density of the powder metallurgy titanium alloy, and effectively reduce defects such as pores and cracks at the interface. The high strength of TiC can serve as a barrier to crack propagation, further improve the mechanical properties of the material, promote the transfer of loads in the powder metallurgy titanium alloy during plastic deformation, avoid local stress concentration, and significantly improve the plasticity and strength of the powder metallurgy titanium alloy.

[0055] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A process for preparing a powder metallurgy titanium alloy, characterized in that: The following steps are involved: The titanium composite powder is prepared by fluidized bed chemical vapor deposition method, zirconium chloride is placed in the gasification section, titanium powder is placed in the fluidized bed reaction section, argon gas is introduced into the system to remove the air in the entire system, and the mass ratio of titanium powder to zirconium chloride is 1: (0.5-0.8); The gasification section is heated to 230-330°C, the fluidized bed reaction section is heated to 550-650°C, argon is continuously introduced into the gasification section and the fluidized bed reaction section, H2 and CH4 are introduced into the fluidized bed reaction section at flow rates of 100-200 mL / min and 200-300 mL / min, respectively, the reaction is continued for 1-1.5 h, H2 and CH4 are turned off, and the mixture is cooled to room temperature in an argon atmosphere to obtain a titanium composite powder; By weight, take 200-240 parts of titanium composite powder, 15-20 parts of aluminum powder, 10-15 parts of molybdenum powder, 8-14 parts of additives, 5-9 parts of auxiliary agents, and 1-3 parts of binder; The titanium composite powder, aluminum powder, molybdenum powder, additives, auxiliary agents and binders are extruded, dried, crushed, sieved, and then subjected to cold isostatic pressing to obtain a blank; The blank is subjected to hot isostatic sintering and heat treatment in sequence to obtain the product.

2. The process for preparing a powder metallurgy titanium alloy according to claim 1, characterized in that: The molding pressure of the cold isostatic pressing process is 300-500MPa, and the holding time is 30-50min.

3. The process for preparing a powder metallurgy titanium alloy according to claim 1, characterized in that: The protective atmosphere for hot isostatic sintering is argon, the sintering temperature is 850-950°C, the holding time is 1-2h, and the holding pressure is 200-300MPa.

4. The process for preparing a powder metallurgy titanium alloy according to claim 1, characterized in that: Heat treatment specifically includes the following steps: At vacuum degree ≤10 -2 Under the condition of Pa, the hot isostatic sintering blank is first heated to 950-990°C at 10°C / min, kept warm for 2-4h, then furnace cooled to 500-600°C, kept warm for 1-1.5h, and finally air cooled to room temperature.

5. The process for preparing a powder metallurgy titanium alloy according to claim 1, characterized in that: The flow rates of argon in the gasification section and the fluidized bed reaction section are 400-500 mL / min and 1000-1100 mL / min respectively.

6. The process for preparing a powder metallurgy titanium alloy according to claim 1, characterized in that: The auxiliary agent is selected from any one of lithium carbonate and lithium chloride.

7. The process for preparing a powder metallurgy titanium alloy according to claim 1, characterized in that: The auxiliary agent is polyethylene glycol.

8. The process for preparing a powder metallurgy titanium alloy according to claim 1, characterized in that: The adhesive is selected from any one of a polyurethane adhesive and an acrylate adhesive.

9. A powder metallurgy titanium alloy prepared by the preparation process of the powder metallurgy titanium alloy according to any one of claims 1 to 8.