Titanium alloy having fine lamellar structure and powder metallurgy process thereof

Abstract

The application provides a titanium alloy with fine lamellar structure and a powder metallurgy process thereof, wherein the powder mixing comprises screening gas atomized spherical Ti-Al-Mo-Zr titanium alloy powder with a particle size distribution of 10-150 mu m, and mixing titanium alloy powder with the same particle size or different particle sizes in different weight proportions; the hot extrusion comprises hot extrusion of cold-pressed titanium alloy after heat preservation under argon protection, the heat preservation temperature is 1000-1200 DEG C, the heat preservation time is 30-45 min, and the extrusion ratio is 6-20. Through component adjustment and optimization and process adjustment and optimization, the application obtains fine lamellar structure similar to the lamellar structure of ordinary powder metallurgy titanium alloy in appearance, but the original beta grain size, alpha cluster size and alpha lamellar thickness size are smaller, and the strength and plasticity are significantly improved. The application also has the characteristics of low cost, high material utilization rate, short process, strong operability and the like, and can further expand the application of powder metallurgy titanium alloy in the field of aerospace.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of titanium alloy materials and processing, and particularly relates to a titanium alloy with fine lamellar structure and a powder metallurgy process thereof. BACKGROUND

[0002] Ti6Al4V alloy is the earliest applied titanium alloy, has high specific strength, good high-temperature stability, excellent corrosion resistance and biological compatibility, and is widely applied in various fields, especially in the field of aerospace. At present, the production of Ti6Al4V alloy has almost accounted for half of the global titanium products, and has become the most widely used titanium alloy.

[0003] At present, Ti6Al4V alloy is mainly produced by casting, forging and powder metallurgy process. The powder metallurgy process can avoid defects such as shrinkage cavity and shrinkage porosity in casting and uneven structure in forging, and has the advantages of high density, uniform structure, controllable composition, near-net-shape forming, high material utilization rate and the like. It has great attraction to the low buy-to-fly ratio, high cost performance and complex structure design requirements of aerospace titanium alloy parts. However, in order to achieve the purpose of dense structure or low deformation resistance, the powder metallurgy production of Ti6Al4V alloy is often carried out above the β phase transformation temperature for a long time. The body-centered cubic structure of β phase will rapidly diffuse during the high-temperature holding stage, which causes the original β grain to coarsen, and further increases the size of α cluster and the thickness of α lamellar in the lamellar structure after slow cooling, which seriously affects the strength and plasticity of the powder metallurgy prepared Ti6Al4V alloy. In order to better promote the application of powder metallurgy technology in the field of titanium alloy aerospace, it is necessary to solve the problem of original β grain coarsening during the high-temperature holding stage of powder metallurgy production of titanium alloy.

[0004] To solve this problem, researchers have added rare earth elements to powder metallurgy Ti6Al4V alloy to form rare earth oxides to pin the original beta grain boundary to reduce the size of the original beta grain, but this method will cause the density to decrease, significantly affect the strength and plasticity, in order to balance the high density and fine lamellar structure, often need to add B or Si element to improve the density, but the rare earth element itself is high cost, which is not conducive to the low cost of titanium alloy. Patent application number CN200910012757.1, the invention name is "a kind of fine lamellar microstructure titanium alloy and its preparation method" proposes that the alloy composition is composed of Al≤6.5%, Sn≤8.0%, Zr 3.0~10.0%, Mo≤1.0%, Si 0.3~0.7%, Nb≤1.0%, Ta≤5.0%, C≤0.08%, the rest is Ti and inevitable impurity elements, by adjusting the content of each element and adjusting the parameters of smelting, hot working and heat treatment process to ensure the existence of silicide to hinder the growth of the original beta grain. The advantage of the invention is only that the high temperature strength is relatively high, but the original beta grain obtained by the invention is still relatively large (below 200 μm), which leads to low room temperature strength and plasticity, and the silicide is easy to coarsen after high temperature service, resulting in low plasticity.

[0005] In order to obtain titanium alloy with smaller original beta grain, the composition of titanium alloy and its powder metallurgy process need to be adjusted in the art, so as to overcome the problem of strength and plasticity reduction caused by the coarsening of the original beta grain in the preparation of titanium alloy in the prior art, while improving the material density, shortening the production process, effectively improving the performance price ratio of the material, and meeting the higher performance requirements of powder metallurgy titanium alloy in the field of aerospace. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art, by adjusting and optimizing the composition of titanium alloy and its powder metallurgy process, to provide a titanium alloy with fine lamellar structure and its powder metallurgy process, to obtain the "fine" lamellar structure similar to the lamellar structure of ordinary powder metallurgy titanium alloy, but with smaller original beta grain size, α cluster size and α lamellar thickness, and significantly improved strength and plasticity.

[0007] The purpose of the present application is achieved by the following technical solutions:

[0008] A powder metallurgy process for a titanium alloy with fine lamellar structure, comprising ingot preparation, gas atomization, powder mixing and hot extrusion, characterized in that:

[0009] The powder mixing comprises the following steps and process conditions:

[0010] The gas atomized spherical Ti-Al-Mo-Zr titanium alloy powder with a particle size distribution of 10-150 μm is sieved, and the gas atomized spherical Ti-Al-Mo-Zr titanium alloy powder with the same particle size or different particle sizes is mixed according to a weight ratio, the mixing machine speed is 200-400 r / min, and the mixing time is 3-5 h.

[0011] The hot extrusion comprises the following steps and process conditions:

[0012] (1) The powder is placed in a ladle cover and cold-pressed, the cold-pressing pressure is 600-800 MPa, and the time is 30-120 s;

[0013] (2) The cold-pressed sample is directly placed in a heating furnace for heat preservation, the heat preservation process is carried out under argon protection, the heat preservation temperature is 1000-1200 ℃, and the heat preservation time is 30-45 min; the extrusion nozzle is directly placed in the heating furnace for heat preservation, the heat preservation temperature is 440-510 ℃, and the heat preservation time is 30-60 min; the extrusion die temperature is 440-560 ℃;

[0014] (3) After the heat preservation is completed, the extrusion nozzle is placed in the extrusion die, and then the sample is placed for hot extrusion, the hot extrusion, the extrusion ratio is 6-20; and the titanium alloy with a fine lamellar structure is obtained after cooling to room temperature, the alloy composition is Al 5.5-7.0%, Mo 2.5-3.5%, Zr 0.5-1.5% according to the weight percentage, and the balance is Ti and inevitable impurities.

[0015] Preferably, the gas atomized spherical Ti-Al-Mo-Zr titanium alloy powder with the same particle size or different particle sizes is mixed according to a weight ratio, the different particle sizes refer to that the gas atomized spherical Ti-Al-Mo-Zr titanium alloy powder with a particle size distribution of 10-150 μm is sieved, and three kinds of particles with a particle size of 10-25 μm, 25-100 μm and 100-150 μm are obtained after sieving, and the weight ratio of 10-25 μm: 25-100 μm: 100-150 μm ranges from (1:11:8) to (4:11:5).

[0016] Preferably, the hot extrusion has an extrusion ratio of 9-12.

[0017] Preferably, the titanium alloy powder metallurgy process comprises the following steps and process parameters:

[0018] Step 1: Ingot preparation

[0019] (1) The original high-purity Ti, Al, Mo and Zr metal particles (purity > 99.99%) are proportioned according to the weight percentage of Al 6.6%, Mo 2.9%, Zr 1.0% and Ti 89.5%;

[0020] (2) Put the original high-purity Mo, Zr metal particles into the arc smelting furnace for smelting, the smelting temperature is 3200~3800℃, the smelting times is 4~6 times, and the Mo-Zr intermediate alloy is obtained;

[0021] (3) Put the Mo-Zr intermediate alloy, original high-purity Ti, Al metal particles into the magnetic suspension smelting furnace for smelting, the smelting temperature is 2100~2700℃, the smelting times is 4~6 times, and the Ti-Al-Mo-Zr alloy ingot with uniform composition is obtained;

[0022] Step 2: Gas atomization powdering

[0023] (1) Put the Ti-Al-Mo-Zr titanium alloy ingot into the gas atomization furnace, and use high-purity argon for atomization, the argon injection speed is 500~800m / s, and the pressure of argon is 8~11MPa;

[0024] (2) Screen the gas atomized spherical Ti-Al-Mo-Zr titanium alloy powder with a particle size distribution of 10~150μm, and after screening, it is 10~25μm, 25~100μm, and 100~150μm three kinds of particles;

[0025] Step 3: Powder mixing

[0026] Put the gas atomized spherical Ti-Al-Mo-Zr titanium alloy powder with different particle sizes into the powder mixer according to the weight ratio, the weight ratio of different particle sizes 10~25μm:25~100μm:100~150μm is 3:11:6, the rotating speed is 300r / min, and the time is 4h;

[0027] Step 4: Hot extrusion

[0028] (1) Put the powder into the 45 steel ladle, and cold press into shape, the cold pressing pressure is 700~800MPa, and the time is 30~60s;

[0029] (2) Put the cold-pressed sample directly into the heating furnace for heat preservation, the heat preservation process is carried out under argon protection, the heat preservation temperature is 1050±20℃, and the heat preservation time is 30min; Put the extrusion nozzle directly into the heating furnace for heat preservation, the heat preservation temperature is 480±10℃, and the heat preservation time is 45min; The extrusion die temperature is 500±10℃;

[0030] (3) After heat preservation, put the extrusion nozzle into the extrusion die first, then put the sample, and then carry out hot extrusion, the extrusion ratio is 11~12; Cool to room temperature, and obtain a kind of titanium alloy with fine lamellar structure, the alloy composition is Al 6.6%, Mo 2.9%, Zr 1.0%, the total amount of impurities is ≤0.25%, and Ti≥89.25%.

[0031] A titanium alloy with fine lamellar structure is prepared by the titanium alloy powder metallurgy process.

[0032] Compared with the prior art, the application has the following advantages and beneficial effects:

[0033] (1) The application provides a titanium alloy with fine lamellar structure (Al 5.5-7.0%, Mo 2.5-3.5%, Zr 0.5-1.5% by weight, and the balance being Ti and inevitable impurities), which removes Si elements and Sn elements for increasing the silicide dissolution temperature and Nb and Ta elements for supplementing strengthening, adjusts the content of Zr elements for increasing the silicide dissolution temperature but refining the structure, increases the content of Mo elements for reducing the diffusion rate of the titanium alloy, slows down the high-temperature diffusion rate by adjusting the element content, refines the original β grains to less than 50 μm under the cooperation of process parameters, and overcomes the insufficient silicide refinement of the original β grains in the prior art. The fine lamellar structure is similar to the lamellar structure of the ordinary powder metallurgy prepared titanium alloy in appearance, but the original β grain size, α cluster size and α lamellar thickness size are smaller, and the strength and plasticity are significantly improved.

[0034] (2) The application provides a titanium alloy with fine lamellar structure and a powder metallurgy process thereof, and high-density, fine lamellar structure, high strength and plasticity titanium alloy can be obtained. As an example, the detection results of the sample of Example 1 show that the density is 99.13%, the original β grain size is 11 μm, the α cluster size is 7 μm, the α lamellar thickness is 0.4 μm, the room temperature tensile strength and the elongation after fracture are significantly improved, and are 1179 MPa and 16.4% respectively, and the 600 ℃ tensile strength and the elongation after fracture reach the performance level of the existing high-temperature titanium alloy, and are 603 MPa and 35% respectively.

[0035] (3) The application can overcome the problem of the decrease of strength and plasticity caused by the coarse original β grain in the preparation of the titanium alloy in the prior art, and also has the characteristics of low cost, high material utilization rate, short process, strong operability and the like, and can further expand the application of the powder metallurgy titanium alloy in the field of aerospace. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A scanning electron microscope image of the titanium alloy with fine lamellar structure described in Example 1;

[0037] Figure 2 A scanning electron microscope image of the titanium alloy with fine lamellar structure described in Example 2;

[0038] Figure 3A scanning electron microscope image of the titanium alloy with fine lamellar structure described in Example 3;

[0039] Figure 4 A scanning electron microscope image of the titanium alloy with fine lamellar structure described in Example 4. DETAILED DESCRIPTION

[0040] The specific implementation of the present application is further illustrated below in conjunction with examples, but the implementation and protection of the present application are not limited to the following examples.

[0041] Example 1

[0042] A titanium alloy powder metallurgy process with fine lamellar structure includes the following steps and process parameters:

[0043] Step 1: Ingot preparation

[0044] (1) The original high-purity Ti, Al, Mo, Zr metal particles (purity > 99.99%) are weighed according to the weight percentage of Al 6.6%, Mo 2.9%, Zr 1.0%, and Ti 89.5%;

[0045] (2) The original high-purity Mo, Zr metal particles are placed in an electric arc smelting furnace for smelting, with a smelting temperature of 3500±20℃ and a smelting frequency of 5 times, to obtain a Mo-Zr intermediate alloy;

[0046] (3) The Mo-Zr intermediate alloy, original high-purity Ti, Al metal particles are placed in a magnetic suspension smelting furnace for smelting, with a smelting temperature of 2400±20℃ and a smelting frequency of 5 times, to obtain a Ti-Al-Mo-Zr alloy ingot with uniform composition;

[0047] Step 2: Gas atomization powdering

[0048] (1) The Ti-Al-Mo-Zr alloy ingot is placed in a gas atomization furnace and atomized using high-purity argon gas, with an argon gas injection speed of 750 m / s and an argon gas pressure of 10 MPa;

[0049] (2) The gas atomized spherical Ti-Al-Mo-Zr alloy powder with a particle size distribution of 10-150 μm is sieved into three types of particles: 10-25 μm, 25-100 μm, and 100-150 μm;

[0050] Step 3: Powder mixing

[0051] The gas atomized spherical Ti-Al-Mo-Zr alloy powder of different particle sizes is weighed and placed in a powder mixer according to the weight ratio, with a weight ratio of 3:11:6 for 10-25 μm: 25-100 μm: 100-150 μm, a rotation speed of 300 r / min, and a time of 4 h.

[0052] Step 4: hot extrusion

[0053] (1) Put the powder into a 45 steel ladle, cold press forming, cold pressing pressure is 800 MPa, time is 30 s;

[0054] (2) Put the cold-pressed sample directly into the heating furnace for heat preservation, the heat preservation process is carried out under argon protection, the heat preservation temperature is 1050±20℃, the heat preservation time is 30 min; Put the extrusion nozzle directly into the heating furnace for heat preservation, the heat preservation temperature is 480±10℃, the heat preservation time is 45 min; The extrusion die temperature is 500±10℃;

[0055] (3) After heat preservation, put the extrusion nozzle in the extrusion die first, then put the sample, and then carry out hot extrusion, the extrusion ratio is 12; Cool to room temperature to obtain a titanium alloy with fine lamellar structure, the alloy composition is Al 6.6%, Mo 2.9%, Zr 1.0%, impurities total amount ≤0.25%, Ti≥89.25% by weight percentage.

[0056] The density is 99.13% by Archimedes drainage method tested on BSA224S electronic analytical balance. The scanning electron microscope image is obtained on SU8220 ultra-high resolution cold field emission scanning electron microscope, as shown in Figure 1 It can be seen that the original β grain size is 11 μm, the α cluster size is 7 μm, and the α lamellar thickness is 0.4 μm. The tensile test is carried out on CMT510 type universal material testing machine, and the room temperature tensile strength is 1179 MPa, and the room temperature elongation after fracture is 16.4%; The tensile strength at 600℃ is 603 MPa, and the elongation after fracture at 600℃ is 35.0%.

[0057] Example 2

[0058] A titanium alloy powder metallurgy process with fine lamellar structure includes the following steps and process parameters:

[0059] Step 1: ingot preparation

[0060] (1) The original high-purity Ti, Al, Mo, Zr metal particles (purity > 99.99%) are proportioned according to the weight percentage of Al 5.5%, Mo 3.5%, Zr 0.5%, and Ti 90.5%;

[0061] (2) Put the original high-purity Mo and Zr metal particles into the electric arc melting furnace for melting, the melting temperature is 3300±20℃, the melting times is 6, and the Mo-Zr intermediate alloy is obtained;

[0062] (3) Put Mo-Zr intermediate alloy, original high-purity Ti, and Al metal particles into a magnetic suspension melting furnace to melt, the melting temperature is 2600±20℃, the melting times is 4, and a Ti-Al-Mo-Zr alloy ingot with uniform composition is obtained;

[0063] Step 2: Gas atomization powdering

[0064] (1) Put the Ti-Al-Mo-Zr alloy ingot into a gas atomization furnace, and use high-purity argon to atomize, the argon jet speed is 600 m / s, and the argon pressure is 8 MPa;

[0065] (2) Screen the gas atomized spherical Ti-Al-Mo-Zr alloy powder with a particle size distribution of 10-150 μm into three kinds of particles with a particle size of 10-25 μm, 25-100 μm and 100-150 μm;

[0066] Step 3: Powder mixing

[0067] Put the gas atomized spherical Ti-Al-Mo-Zr alloy powder with different particle sizes into a powder mixer according to the weight ratio, the weight ratio of the different particle sizes 10-25 μm: 25-100 μm: 100-150 μm is 4:11:5, the rotating speed is 400 r / min, and the time is 3 h;

[0068] Step 4: Hot extrusion

[0069] (1) Put the powder into a 45 steel ladle, and cold-press form, the cold-press pressure is 700 MPa, and the time is 60 s;

[0070] (2) Put the cold-pressed sample directly into a heating furnace for heat preservation, the heat preservation process is carried out under argon protection, the heat preservation temperature is 1150±20℃, and the heat preservation time is 45 min; put the extrusion nozzle directly into the heating furnace for heat preservation, the heat preservation temperature is 500±10℃, and the heat preservation time is 60 min; the extrusion die temperature is 550±10℃;

[0071] (3) After the heat preservation is completed, put the extrusion nozzle into the extrusion die first, then put the sample, and then perform hot extrusion, the extrusion ratio is 9; cool to room temperature, and a titanium alloy with a fine lamellar structure is obtained, the alloy composition is Al 5.5%, Mo 3.5%, Zr 0.5% according to the weight percentage, the total amount of impurities is ≤0.25%, and Ti is ≥90.25%.

[0072] The compactness is 99.24% obtained by the Archimedes drainage method on a BSA224S electronic analytical balance. The scanning electron microscope image is obtained on a SU8220 ultra-high resolution cold field emission scanning electron microscope, Figure 2As shown, it can be seen that the original β grain size is 23 μm, the α cluster size is 7 μm, and the α sheet thickness is 0.4 μm. The tensile test is carried out on the CMT510 type universal material testing machine, and it is tested that the room temperature tensile strength is 1121 MPa, and the room temperature elongation after fracture is 14.3%; the 600 ℃ tensile strength is 569 MPa, and the 600 ℃ elongation after fracture is 29.7%.

[0073] Example 3

[0074] A titanium alloy powder metallurgy process with fine sheet structure includes the following steps and process parameters:

[0075] Step 1: Ingot preparation

[0076] (1) The original high-purity Ti, Al, Mo, Zr metal particles (purity > 99.99%) are prepared according to the weight percentage of Al 7.0%, Mo 2.5%, Zr 1.5%, and Ti 89.0%;

[0077] (2) The original high-purity Mo and Zr metal particles are placed in an electric arc smelting furnace for smelting, the smelting temperature is 3700±20℃, the smelting times are 4 times, and a Mo-Zr intermediate alloy is obtained;

[0078] (3) The Mo-Zr intermediate alloy, original high-purity Ti and Al metal particles are placed in a magnetic suspension smelting furnace for smelting, the smelting temperature is 2200±20℃, the smelting times are 6 times, and a Ti-Al-Mo-Zr alloy ingot with uniform composition is obtained;

[0079] Step 2: Gas atomization powdering

[0080] (1) The Ti-Al-Mo-Zr alloy ingot is placed in a gas atomization furnace, and high-purity argon is used for atomization, the argon injection speed is 500 m / s, and the argon pressure is 11 MPa;

[0081] (2) The gas atomized spherical Ti-Al-Mo-Zr alloy powder with a particle size distribution of 10-150 μm is sieved into three kinds of particles of 10-25 μm, 25-100 μm and 100-150 μm;

[0082] Step 3: Powder mixing

[0083] The gas atomized spherical Ti-Al-Mo-Zr alloy powder with different particle sizes is put into a powder mixer according to the weight ratio, the weight ratio of different particle sizes 10-25 μm: 25-100 μm: 100-150 μm is 1:11:8, the rotating speed is 200 r / min, and the time is 5 h;

[0084] Step 4: Hot extrusion

[0085] (1) Put the powder into a 45 steel ladle, cold press forming, cold pressing pressure is 600 MPa, time is 120 s;

[0086] (2) Put the cold-pressed sample directly into the heating furnace for heat preservation, the heat preservation process is carried out under argon protection, the heat preservation temperature is 1050±20℃, the heat preservation time is 30 min; Put the extrusion nozzle directly into the heating furnace for heat preservation, the heat preservation temperature is 450±10℃, the heat preservation time is 30 min; The extrusion die temperature is 450±10℃;

[0087] (3) After heat preservation, put the extrusion nozzle into the extrusion die first, then put the sample, and then carry out hot extrusion, the extrusion ratio is 6; Cool to room temperature, thereby obtaining a titanium alloy with fine lamellar structure, the alloy composition is Al 7.0%, Mo 2.5%, Zr 1.5%, the total amount of impurities is ≤0.25%, and Ti≥88.75% by weight percentage.

[0088] The compactness is 98.95% tested by Archimedes drainage method on a BSA224S electronic analytical balance. The scanning electron microscope image is obtained on a SU8220 ultra-high resolution cold field emission scanning electron microscope, as shown in Figure 3 It can be seen that the original β grain size is 43 μm, the α cluster size is 6 μm, and the α lamellar thickness is 0.5 μm. The tensile test is carried out on a CMT510 type universal material testing machine, and the room temperature tensile strength is 1133 MPa, and the room temperature elongation after fracture is 15.0%; The tensile strength at 600℃ is 580 MPa, and the elongation after fracture at 600℃ is 33.5%.

[0089] Example 4

[0090] A titanium alloy powder metallurgy process with fine lamellar structure includes the following steps and process parameters:

[0091] Step 1: Ingot preparation

[0092] (1) The original high-purity Ti, Al, Mo, Zr metal particles (purity > 99.99%) are proportioned according to the weight percentage of Al 6.0%, Mo 3.0%, Zr 1.0%, and Ti 90.0%;

[0093] (2) Put the original high-purity Mo and Zr metal particles into the electric arc melting furnace for melting, the melting temperature is 3500±20℃, the melting times is 5, and the Mo-Zr intermediate alloy is obtained;

[0094] (3) Put Mo-Zr intermediate alloy, original high-purity Ti, and Al metal particles into a magnetic suspension melting furnace to melt, the melting temperature is 2400±20℃, the melting times is 5, and a Ti-Al-Mo-Zr alloy ingot with uniform composition is obtained;

[0095] Step 2: Gas atomization powdering

[0096] (1) Put the Ti-Al-Mo-Zr alloy ingot into a gas atomization furnace, and use high-purity argon gas for atomization, the argon gas jet speed is 800 m / s, and the pressure of the argon gas is 10 MPa;

[0097] (2) Screen the gas atomized spherical Ti-Al-Mo-Zr alloy powder with a particle size distribution of 10-150 μm, and screen out particles with a particle size of 25-100 μm;

[0098] Step 3: Powder mixing

[0099] Put the gas atomized spherical Ti-Al-Mo-Zr alloy powder with a particle size of 25-100 μm into a powder mixer to mix the powder, the rotation speed is 300 r / min, and the time is 4 h;

[0100] Step 4: Hot extrusion

[0101] (1) Put the powder into a 45 steel jacket, and cold press into shape, the cold pressing pressure is 800 MPa, and the time is 30 s;

[0102] (2) Put the cold-pressed sample directly into a heating furnace for heat preservation, the heat preservation process is carried out under argon protection, the heat preservation temperature is 1050±20℃, and the heat preservation time is 30 min; put the extrusion nozzle directly into the heating furnace for heat preservation, the heat preservation temperature is 500±10℃, and the heat preservation time is 45 min; the extrusion die temperature is 500±10℃;

[0103] (3) After heat preservation, put the extrusion nozzle into the extrusion die first, then put the sample, and then carry out hot extrusion, the extrusion ratio is 20; cool to room temperature, and a titanium alloy with a fine lamellar structure is obtained, the alloy composition is Al 6.0%, Mo 3.0%, Zr 1.0%, the total amount of impurities is ≤0.25%, and Ti≥ 89.75% by weight percentage.

[0104] The density is 99.40% tested by Archimedes drainage method on a BSA224S electronic analytical balance. The scanning electron microscope image is obtained on a SU8220 ultra-high resolution cold field emission scanning electron microscope, as shown in Figure 4As shown, the original β grain size is 7 μm, the α cluster size is 4 μm, and the α sheet thickness is 0.4 μm. The tensile test is carried out on a CMT510 universal material testing machine, and the results show that the tensile strength at room temperature is 1168 MPa, the elongation at room temperature is 14.7%, the tensile strength at 600℃ is 597 MPa, and the elongation at 600℃ is 31.4%.

Claims

1. A titanium alloy powder metallurgy process with a fine lamellar structure, comprising ingot preparation, gas atomization powder preparation, powder mixing, and hot extrusion, characterized in that: The powder mixing process includes the following steps and their process conditions: The gas-atomized spherical Ti-Al-Mo-Zr titanium alloy powder with a particle size distribution of 10~150μm was sieved, and the gas-atomized spherical Ti-Al-Mo-Zr titanium alloy powders with the same or different particle sizes were mixed in a weight ratio. The mixing machine speed was 200~400r / min, and the mixing time was 3~5h. The hot extrusion includes the following steps and process conditions: (1) Place the powder into a steel sleeve and cold press it into shape. The cold pressing pressure is 600~800MPa and the time is 30~120s; (2) The cold-pressed sample is placed directly into the heating furnace for heat preservation. The heat preservation process is carried out under argon protection. The heat preservation temperature is 1000~1200℃ and the heat preservation time is 30~45min. The extrusion nozzle is placed directly into the heating furnace for heat preservation. The heat preservation temperature is 440~510℃ and the heat preservation time is 30~60min. The temperature of the extrusion die is 440~560℃. (3) After the heat preservation is completed, the extrusion nozzle is placed in the extrusion mold, and then the sample is placed in for hot extrusion. The hot extrusion has an extrusion ratio of 6 to 20. After cooling to room temperature, a titanium alloy with a fine lamellar structure is obtained. The alloy composition by weight percentage is Al 5.5 to 7.0%, Mo 2.5 to 3.5%, Zr 0.5 to 1.5%, with the balance being Ti and unavoidable impurities.

2. The titanium alloy powder metallurgy process with a fine lamellar structure according to claim 1, characterized in that, The process involves mixing gas-atomized spherical Ti-Al-Mo-Zr titanium alloy powders of the same or different particle sizes in a specific weight ratio. The different particle sizes refer to the following: gas-atomized spherical Ti-Al-Mo-Zr titanium alloy powders with a particle size distribution of 10~150μm are sieved, resulting in three particle sizes: 10~25μm, 25~100μm, and 100~150μm. The weight ratio of 10~25μm:25~100μm:100~150μm is in the range of (1:11:8) to (4:11:5).

3. The titanium alloy powder metallurgy process with a fine lamellar structure according to claim 1, characterized in that, The hot extrusion has an extrusion ratio of 9 to 12.

4. A titanium alloy powder metallurgy process with a fine lamellar structure according to claim 1, 2, or 3, characterized in that, The titanium alloy powder metallurgy process includes the following steps and their process parameters: Step 1: Ingot Preparation (1) The original high-purity Ti, Al, Mo and Zr metal particles were mixed according to the following weight percentages: Al 6.6%, Mo 2.9%, Zr 1.0% and Ti 89.5%; (2) Place the original high-purity Mo and Zr metal particles into an electric arc melting furnace for melting at a temperature of 3200~3800℃ and for 4~6 melting times to obtain a Mo-Zr master alloy. (3) Mo-Zr master alloy, original high-purity Ti and Al metal particles are placed in a magnetic levitation melting furnace for melting. The melting temperature is 2100~2700℃ and the melting times are 4~6 times to obtain a Ti-Al-Mo-Zr alloy ingot with uniform composition. Step 2: Gas atomization powder production (1) Place the Ti-Al-Mo-Zr titanium alloy ingot into a gas atomizing furnace and atomize it with high-purity argon gas. The argon gas injection speed is 500~800m / s and the argon gas pressure is 8~11MPa. (2) The gas-atomized spherical Ti-Al-Mo-Zr titanium alloy powder with a particle size distribution of 10~150μm was sieved and the sieved particles were 10~25μm, 25~100μm, and 100~150μm. Step 3: Mix the powders Different particle sizes of gas-atomized spherical Ti-Al-Mo-Zr titanium alloy powders were added to a powder mixer in a weight ratio of 3:11:6 for the different particle sizes of 10~25μm:25~100μm:100~150μm. The mixing time was 4h. Step 4: Hot extrusion (1) Place the powder into a 45 steel sleeve and cold press it into shape. The cold pressing pressure is 700~800MPa and the time is 30~60s. (2) The cold-pressed sample is placed directly into the heating furnace for heat preservation. The heat preservation process is carried out under argon protection. The heat preservation temperature is 1050±20℃ and the heat preservation time is 30min. The extrusion nozzle is placed directly into the heating furnace for heat preservation. The heat preservation temperature is 480±10℃ and the heat preservation time is 45min. The temperature of the extrusion die is 500±10℃. (3) After the heat preservation is completed, the extrusion nozzle is first placed in the extrusion mold, followed by the sample, and then hot extrusion is performed. The extrusion ratio is 11~12. After cooling to room temperature, a titanium alloy with fine lamellar structure is obtained with the following alloy composition by weight percentage: Al 6.6%, Mo 2.9%, Zr 1.0%, total impurities ≤0.25%, and Ti ≥ 89.25%.

5. A titanium alloy having a fine lamellar structure, characterized in that... The titanium alloy is prepared by the powder metallurgy process according to any one of claims 1 to 4.

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