Ti-based alloy powder and preparation method thereof

Abstract

The invention discloses Ti-based alloy powder, which is prepared from the nominal components in percentage by atom: (5 to 10) of Ti, (2 to 5) of Al, (1 to 3) of V, (0.5 to 2.0) of Y2O3 and the balance of Ti and inevitable impurities, the preparation method comprises the following steps: 1, weighing raw material powder; 2, charging and sealing; 3, ball milling; and 4, discharging to obtain Ti-based alloy powder. According to the Ti-based alloy powder disclosed by the invention, high-volume nano Y2O3 is introduced and uniformly dispersed in a Ti matrix to form a dispersion strengthening phase, so that the room-temperature and high-temperature strength, creep resistance and thermal stability of the alloy are improved; according to the mechanical alloying process, the ball-to-material ratio, the rotating speed and the time of ball milling are strictly controlled, intermittent ball milling and external cooling are adopted to control temperature rise and pollution, it is guaranteed that Y2O3 forms nanocrystalline and a dispersion strengthening phase in a Ti matrix, the strength, hardness and thermal stability of the alloy are improved, the process is controllable, and repeatability is good.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials technology, specifically relating to a Ti-based alloy powder and its preparation method. Background Technology

[0002] Titanium and titanium alloys are widely used in aerospace, biomedical, and chemical industries due to their high specific strength, excellent corrosion resistance, and good biocompatibility. While traditional titanium alloys (such as TC4, or Ti-6Al-4V) have excellent overall performance, there is still room for improvement in their strength, wear resistance, and high-temperature performance. Furthermore, titanium alloys prepared by traditional casting processes suffer from compositional segregation and coarse microstructure, limiting further performance enhancements.

[0003] Powder metallurgy, particularly mechanical alloying, offers a new approach to preparing high-performance titanium alloys. Mechanical alloying is a solid-state process that uses high-energy ball milling to repeatedly deform, cold-weld, and fracture powder particles, thereby achieving atomic-level alloying. It can produce microstructures that are difficult to achieve using traditional casting methods, such as ultrafine-grained, amorphous, or nanocrystalline structures, and can introduce reinforcing phases such as high-density oxides and nitrides, significantly improving the strength, hardness, and thermal stability of the alloy.

[0004] However, existing mechanical alloying processes for preparing Ti-based alloy powders still face some challenges: (1) Easily contaminated: During long-term ball milling, the powder is prone to react with the grinding balls, the jar or the grinding atmosphere, introducing impurities such as Fe, O, and N, which deteriorates the plasticity and fatigue properties of the alloy.

[0005] (2) Unstable process: The selection of ball milling parameters (such as ball-to-material ratio, rotation speed and time) has a great impact on the microstructure and properties of the final powder. The lack of an optimized process window may lead to incomplete alloying or excessive powder hardening.

[0006] (3) Insufficient performance designability: Conventional Ti-Al-V alloys have limited performance improvement after mechanical alloying, and new composition systems need to be developed to give full play to the technical advantages of mechanical alloying.

[0007] Therefore, there is a need to provide a Ti-based alloy powder with reasonable composition design, significant strengthening effect and controllable process, as well as its preparation method, to overcome the shortcomings of the existing technology. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a Ti-based alloy powder that addresses the shortcomings of the prior art. This Ti-based alloy powder introduces high-volume nano-Y₂O₃ and uniformly disperses it within a Ti matrix, forming a high-density, thermally stable dispersed reinforcing phase. This effectively pins grain boundaries, inhibits grain growth at high temperatures, and significantly improves the room-temperature and high-temperature strength, creep resistance, and thermal stability of the Ti-based alloy, thus solving the problem of insufficient strength and high-temperature performance of existing titanium-based alloys.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a Ti-based alloy powder, characterized in that the nominal composition by atomic percentage is: Ti-(5-10)Al-(2-5)V-(1-3)Mo-(0.5-2.0)Y2O3, with the balance being Ti and unavoidable impurities.

[0010] The above-mentioned Ti-based alloy powder is characterized in that the raw materials of the Ti-based alloy powder include: Ti, Al, V, and Mo powders with a particle size of 10μm to 45μm, and Y2O3 nanoparticles with a particle size of 20nm to 50nm.

[0011] The above-mentioned Ti-based alloy powder is characterized in that the average particle size of the Ti-based alloy powder is 3μm~6μm, and the Y2O3 particles are uniformly dispersed in the titanium matrix.

[0012] Meanwhile, this invention also discloses a method for preparing Ti-based alloy powder as described above, characterized in that it employs a mechanical alloying method, comprising the following steps: Step 1, Ingredients: Weigh the raw materials, including elemental powders and Y2O3 powder, according to the nominal composition of the Ti-based alloy powder; Step 2, Loading and Sealing: Load the elemental powders and Y2O3 powder weighed in Step 1 and the grinding balls into the ball mill jar, evacuate the jar and fill it with inert protective gas. Step 3, Mechanical alloying: Place the ball mill jar filled with inert protective gas in Step 2 into a planetary ball mill for ball milling. The ball milling speed is 250 rpm to 400 rpm and the ball milling time is 20 h to 60 h. Step 4, Discharge and Collection: Collect the alloy powder obtained after ball milling in Step 3 under a protective atmosphere to obtain Ti-based alloy powder.

[0013] The method described above is characterized in that the grinding balls in step two are cemented carbide balls, and the ball-to-material ratio is 10:1 to 20:1. Typically, cemented carbide balls of different diameters are used, with a preferred mass ratio of 1:2 to improve grinding efficiency.

[0014] The method described above is characterized in that the inert protective gas in step two is high-purity argon.

[0015] The method described above is characterized in that the ball milling in step three adopts an intermittent ball milling mode, that is, the ball milling is stopped for an intermittent period of time.

[0016] The method described above is characterized in that the intermittent ball milling mode consists of ball milling for 30 minutes followed by an intermittent 10-minute interval.

[0017] The method described above is characterized in that, in step three, the ball milling jar is cooled to control the temperature of the ball milling process to be below 50°C.

[0018] Compared with the prior art, the present invention has the following advantages: 1. The Ti-based alloy powder of the present invention employs multi-component solid solution strengthening on the one hand: by adding Al and V as α and β stabilizing elements, solid solution strengthening is provided, thereby improving the strength and hardness of the Ti-based alloy. By adding Mo as a strong β stabilizing element, the stability of the β phase is further improved, thereby enhancing the strength and heat resistance of the Ti-based alloy. On the other hand, nano-oxide dispersion strengthening is employed: by introducing nano-Y2O3 and uniformly dispersing it in the Ti matrix, a high-density, thermally stable dispersion strengthening phase is formed, which can effectively pin grain boundaries, inhibit grain growth at high temperatures, and significantly improve the room temperature and high temperature strength, creep resistance, and thermal stability of the Ti-based alloy.

[0019] 2. Compared with traditional gas atomization after melting, the present invention introduces nano-Y2O3 into the Ti matrix by mechanical alloying, which is highly operable, has low equipment requirements, and is low in cost and easy to implement.

[0020] 3. By precisely controlling the rotation speed and time of the ball mill and using a high ball-to-material ratio, this invention achieves intense plastic deformation and cold welding fracture cycles, forcing element atoms to diffuse into each other and ultimately forming a uniform nanocrystalline structure, providing extremely high strength for Ti-based alloys.

[0021] 4. This invention effectively controls temperature rise by using cemented carbide grinding balls, high-purity argon gas protection, and intermittent ball milling combined with external cooling. This minimizes the reaction between powder and grinding balls, canisters, or grinding atmosphere, and reduces the introduction of impurities such as Fe, O, and N, ensuring the purity of Ti-based alloy powder and preventing deterioration of the alloy's plasticity and fatigue properties.

[0022] 5. The preparation method of the present invention has a clear range of process parameters, is highly operable, and has good process repeatability, which is conducive to quality control and large-scale preparation in industrial production.

[0023] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0024] Example 1 The nominal composition of the Ti-based alloy powder in this embodiment, by atomic percentage, is: Ti-5Al-2V-1Mo-0.5Y2O3, with the balance being Ti and unavoidable impurities.

[0025] The Ti-based alloy powder preparation method in this embodiment adopts mechanical alloying and includes the following steps: Step 1, Ingredients: Weigh out Ti powder, Al powder, V powder, Mo powder and Y2O3 powder with an average particle size of 20nm to 50nm according to the nominal composition of Ti-based alloy powder. Step 2, Loading and Sealing: The Ti powder, Al powder, V powder, Mo powder, and Y₂O₃ powder weighed in Step 1, along with the cemented carbide grinding balls, are loaded into the grinding jar at a ball-to-material ratio of 10:1, with a large to small ball mass ratio of 1:2. The grinding jar is then evacuated to a vacuum of 10... -3 After Pa, high-purity argon gas with a volume purity of 99.999% is introduced as an inert protective gas, and the vacuuming and introduction of high-purity argon gas are repeated three times. Step 3, Mechanical alloying: The grinding jar filled with inert protective gas in Step 2 is fixed on a planetary ball mill for ball milling. The ball milling speed is 250 rpm and the ball milling time is 20 h. An intermittent ball milling mode of 30 min ball milling followed by 10 min interval is adopted. The grinding jar is forced to be cooled by air during ball milling to control the temperature of the ball milling process to be below 40℃. Step 4, Discharge and Collection: After ball milling, open the ball mill jar in an argon-protected glove box to collect the alloy powder obtained after ball milling in Step 3, thus obtaining Ti-based alloy powder.

[0026] Comparative Example 1 The difference between this comparative example and Example 1 is that Y2O3 powder is not added to the composition of the Ti-based alloy powder, and the nominal composition by atomic percentage is: Ti-5Al-2V-1Mo.

[0027] Ti-based alloy powders from Example 1 and Comparative Example 1 of the present invention were subjected to hot isostatic pressing (HIP) sintering under the same conditions to form an alloy, and its room temperature mechanical properties were tested. The results showed that the tensile strength of the alloy from Example 1 reached 1450 MPa, which was much higher than that of Comparative Example 1 (1100 MPa), while maintaining considerable plasticity. This indicates that the nano-Y2O3 added to the Ti-based alloy powder in the present invention has a significant dispersion strengthening effect, significantly improving the strength of the alloy.

[0028] Example 2 The nominal composition of the Ti-based alloy powder in this embodiment, by atomic percentage, is: Ti-7Al-3V-2Mo-1.0Y2O3, with the balance being Ti and unavoidable impurities.

[0029] The Ti-based alloy powder preparation method in this embodiment adopts mechanical alloying and includes the following steps: Step 1, Ingredients: Weigh out Ti powder, Al powder, V powder, Mo powder and Y2O3 powder with an average particle size of 20nm to 50nm according to the nominal composition of Ti-based alloy powder. Step 2, Loading and Sealing: The Ti powder, Al powder, V powder, Mo powder, and Y₂O₃ powder weighed in Step 1, along with the cemented carbide grinding balls, are loaded into the grinding jar. The ball-to-powder ratio is 15:1, with a large to small ball mass ratio of 1:2. The grinding jar is then evacuated to 10°C. -3 After Pa, high-purity argon gas with a volume purity of 99.999% is introduced as an inert protective gas, and the vacuuming and introduction of high-purity argon gas are repeated three times. Step 3, Mechanical alloying: The grinding jar filled with inert protective gas in Step 2 is fixed on a planetary ball mill for ball milling. The ball milling speed is 300 rpm and the ball milling time is 40 h. An intermittent ball milling mode of 30 min ball milling followed by 10 min interval is adopted. The grinding jar is forced to be cooled by air during ball milling to control the temperature of the ball milling process below 40℃. Step 4, Discharge and Collection: After ball milling, open the ball mill jar in an argon-protected glove box to collect the alloy powder obtained after ball milling in Step 3, thus obtaining Ti-based alloy powder.

[0030] Example 3 The nominal composition of the Ti-based alloy powder in this embodiment, by atomic percentage, is: Ti-10Al-5V-3Mo-2Y2O3, with the balance being Ti and unavoidable impurities.

[0031] The Ti-based alloy powder preparation method in this embodiment adopts mechanical alloying and includes the following steps: Step 1, Ingredients: Weigh out Ti powder, Al powder, V powder, Mo powder and Y2O3 powder with an average particle size of 20nm to 50nm according to the nominal composition of Ti-based alloy powder. Step 2, Loading and Sealing: The Ti powder, Al powder, V powder, Mo powder, and Y2O3 powder weighed in Step 1, along with the cemented carbide grinding balls, are loaded into the grinding jar at a ball-to-material ratio of 20:1, with a large to small ball mass ratio of 1:2. The grinding jar is then evacuated to a vacuum of 10... -3 After Pa, high-purity argon gas with a volume purity of 99.999% is introduced as an inert protective gas, and the vacuuming and introduction of high-purity argon gas are repeated three times. Step 3, Mechanical alloying: The grinding jar filled with inert protective gas in Step 2 is fixed on a planetary ball mill for ball milling. The ball milling speed is 400 rpm and the ball milling time is 60 h. An intermittent ball milling mode of 30 min ball milling followed by 10 min interval is adopted. The grinding jar is forced to be cooled by air during ball milling to control the temperature of the ball milling process below 40℃. Step 4, Discharge and Collection: After ball milling, open the ball mill jar in an argon-protected glove box to collect the alloy powder obtained after ball milling in Step 3, thus obtaining Ti-based alloy powder.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A Ti-based alloy powder, characterized in that, The nominal composition, in atomic percentage, is: Ti-(5-10)Al-(2-5)V-(1-3)Mo-(0.5-2.0)Y2O3, with the balance being Ti and unavoidable impurities.

2. The Ti-based alloy powder according to claim 1, characterized in that, The raw materials for the Ti-based alloy powder include: Ti, Al, V, and Mo powders with a particle size of 10μm to 45μm, and Y2O3 nanopowder with a particle size of 20nm to 50nm.

3. The Ti-based alloy powder according to claim 1, characterized in that, The average particle size of the Ti-based alloy powder is 3μm~6μm, and the Y2O3 particles are uniformly dispersed in the titanium matrix.

4. A method for preparing Ti-based alloy powder as described in any one of claims 1 to 3, characterized in that, The mechanical alloying method includes the following steps: Step 1, Ingredients: Weigh the raw materials, including elemental powders and Y2O3 powder, according to the nominal composition of the Ti-based alloy powder; Step 2, Loading and Sealing: Load the elemental powders and Y2O3 powder weighed in Step 1 and the grinding balls into the ball mill jar, evacuate the jar and fill it with inert protective gas. Step 3, Mechanical alloying: Place the ball mill jar filled with inert protective gas in Step 2 into a planetary ball mill for ball milling. The ball milling speed is 250 rpm to 400 rpm and the ball milling time is 20 h to 60 h. Step 4, Discharge and Collection: Collect the alloy powder obtained after ball milling in Step 3 under a protective atmosphere to obtain Ti-based alloy powder.

5. The method according to claim 4, characterized in that, The grinding balls used in step two are cemented carbide balls, with a ball-to-material ratio of 10:1 to 20:

1.

6. The method according to claim 4, characterized in that, The inert protective gas mentioned in step two is high-purity argon.

7. The method according to claim 4, characterized in that, The ball mill described in step three adopts an intermittent ball milling mode, that is, the ball mill is stopped for a break after running for a period of time.

8. The method according to claim 7, characterized in that, The intermittent ball milling mode consists of 30 minutes of ball milling followed by a 10-minute interval.

9. The method according to claim 4, characterized in that, In step three, the ball milling jar is cooled during ball milling to control the temperature below 50°C.