Fine-grained high-density titanium-aluminum alloy and preparation method thereof

Abstract

The present invention discloses a fine-grained and highly dense titanium aluminide alloy and a preparation method thereof. The raw materials of the fine-grained and highly dense titanium aluminide alloy include Ti, Al, and YbB6, wherein the mass fraction of YbB6 is 0.2 - 0.5%. YbB6 powder is added to the titanium aluminide alloy. During the sintering process, YbB6 reacts with Ti and Al, absorbs the oxygen entering the matrix, and generates rare earth oxide Yb2O3, achieving the purpose of purifying the matrix and having the effect of oxide dispersion strengthening at the same time. At the same time, a second phase TiB with a dispersed distribution is generated. While the grain refinement effect is further optimized, the strength of the sintered titanium aluminide alloy is greatly improved, thereby obtaining a titanium aluminide alloy with fine grains, high density, high strength, and good toughness.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a fine-grained high-density titanium-aluminum alloy and a preparation method thereof. Background Art

[0002] As a structural material, titanium aluminum alloy has the advantages of high specific strength, low density, good creep resistance and good oxidation resistance. As a structural material, it is expected to replace nickel-based alloys at 600℃-900℃, which can significantly reduce the thrust-to-weight ratio and improve fuel efficiency. However, with the continuous development of the aerospace field, the requirements for titanium aluminum alloys are more stringent. Due to the coarse and uneven structure of traditional cast titanium aluminum alloys, the mechanical properties of titanium aluminum alloys are greatly reduced, making it difficult to meet the stringent requirements of the aerospace field. At present, there are many ways to improve the structure of titanium aluminum alloys, such as heat treatment, adding alloying elements, etc. However, most of them have disadvantages such as complex processes, high equipment requirements, and high costs.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The object of the present invention is to provide a fine-grained high-density titanium-aluminum alloy and a preparation method thereof.

[0005] The present invention is achieved in that:

[0006] In a first aspect, the present invention provides a fine-grained high-density titanium-aluminum alloy, the raw materials of which include Ti, Al and YbB6, wherein the mass fraction of YbB6 is 0.2-0.5%.

[0007] In an optional embodiment, dispersed TiB and Yb2O3 are included.

[0008] In an optional embodiment, the mass ratio of Ti to Al in the raw material is 50-60:40-50.

[0009] In a second aspect, the present invention provides a method for preparing the fine-grained high-density titanium-aluminum alloy as described in any one of the aforementioned embodiments, wherein raw materials are mixed in proportion and then sintered to obtain a fine-grained high-density titanium-aluminum alloy.

[0010] In an optional embodiment, the raw material satisfies at least one of the following items ①-②:

[0011] ① The raw materials include Ti powder, Al powder and YbB6 powder;

[0012] ② The particle size of the Ti powder is 30-70 μm; the particle size of the Al powder is 20-50 μm; and the particle size of the YbB6 powder is 10-50 μm.

[0013] In an alternative embodiment, the mixing step comprises ball milling.

[0014] In an optional embodiment, the ball milling mixing satisfies at least one of the following items ①-②:

[0015] ① The grinding balls of the ball mill are composed of 15mm, 10mm and 5mm in diameter in a mass ratio of 3-5:3-5:2;

[0016] ② The ball-to-material ratio of the ball mill is 10-15:1, the filling coefficient of the ball mill jar is 0.4-0.5, the ball mill speed is 200-400r / min, and the ball mill time is 10-12h.

[0017] In an optional embodiment, the materials are mixed without balls after the ball milling, and at least one of the following items ①-② is met;

[0018] ① The ball-milled material is mixed in a three-dimensional mixer without balls, the mixing speed is 30-40 rpm, and the mixing time is 12-24 hours;

[0019] ② After the ball milling, ball-free mixing is performed, and the ball milling and / or ball-free mixing is performed under protective gas conditions.

[0020] In an optional embodiment, the sintering is performed in a spark plasma sintering furnace.

[0021] In an optional embodiment, the sintering satisfies at least one of the following items ①-④;

[0022] ① The sintering is to load the mixed raw materials into a graphite mold and then carry out the sintering in a spark plasma sintering furnace, and the ratio of the height of the graphite mold to the height of the loaded materials is 1:0.4-0.6;

[0023] ② During the sintering, the spark plasma sintering furnace pressure is less than 1×10 -2 Pa;

[0024] ③ The sintering temperature is 1100-1300℃; the sintering holding time is 5-10min; the sintering pressure is 30-40MPa; the sintering rate is 100-120℃ / min;

[0025] ④ The sintering temperature is 1200℃; the sintering holding time is 5min; the sintering pressure is 40MPa; and the sintering rate is 120℃ / min.

[0026] The present invention has the following beneficial effects:

[0027] In the titanium-aluminum alloy of the present application, YbB6 powder is added. During the sintering process, YbB6 reacts with Ti and Al, absorbs oxygen entering the matrix, and generates rare earth oxide Yb2O3, thereby achieving the purpose of purifying the matrix while having the effect of oxide dispersion strengthening; at the same time, a dispersed second phase TiB is generated, and the grain refinement effect is further optimized, while greatly improving the strength of the sintered titanium-aluminum alloy, thereby obtaining a titanium-aluminum alloy with fine grains, high density, high strength and good toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 The electron backscatter diffraction organization diagrams obtained for the examples and comparative examples of the present application: (a) comparative example 1; (b) example 3.

[0030] Figure 2 This is a high-magnification tissue diagram of Example 3. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0032] The embodiment of the present application provides a fine-grained high-density titanium-aluminum alloy, the raw materials of which include Ti, Al and YbB6, wherein the mass fraction of YbB6 is 0.2-0.5%.

[0033] In this embodiment, YbB6 powder is added to the titanium-aluminum alloy. During the sintering process, YbB6 reacts with Ti and Al, absorbs oxygen entering the matrix, and generates rare earth oxide Yb2O3, thereby achieving the purpose of purifying the matrix while having the effect of oxide dispersion strengthening; at the same time, a dispersed second phase TiB is generated, and the grain refinement effect is further optimized, while greatly improving the strength of the sintered titanium-aluminum alloy, thereby obtaining a titanium-aluminum alloy with fine grains, high density, high strength and good toughness.

[0034] The amount of YbB6 powder is controlled within this range, which can effectively ensure that the density of the sintered sample is better, and the grains of the sintered sample are fine and the mechanical properties are excellent. When the amount of YbB6 powder is too small, the grains after sintering will be relatively coarse, and the grain refinement effect will not be obvious, so it is difficult to achieve the purpose of improving tensile strength, yield strength and plasticity; and when the amount of YbB6 powder is too much, the Yb2O3 generated by the added YbB6 in the sintered product will segregate at the grain boundary, produce defects, and cause a decrease in performance.

[0035] In some embodiments of the present application, dispersed TiB and Yb2O3 are included.

[0036] In some embodiments of the present application, the mass ratio of Ti and Al in the raw material is 50-60:40-50, and the obtained titanium aluminum alloy has more advantages in grain fineness, density, strength and toughness than titanium aluminum alloys with other ratios. In some preferred embodiments, the mass ratio of Ti and Al is 55:45.

[0037] Another embodiment of the present application provides a method for preparing the fine-grained high-density titanium-aluminum alloy as described in any one of the aforementioned embodiments, wherein the raw materials are mixed in proportion and then sintered to obtain the fine-grained high-density titanium-aluminum alloy. Compared with the prior art, this embodiment has the advantages of simple and easy control of the preparation process and low production cost, and can therefore also be used to produce small devices, and is widely used in the fields of aerospace and precision medical device manufacturing.

[0038] In some embodiments of the present application, the raw material satisfies at least one of the following items ①-②:

[0039] ① The raw materials include Ti powder, Al powder and YbB6 powder;

[0040] ② The particle size of the Ti powder is 30-70 μm; the particle size of the Al powder is 20-50 μm; and the particle size of the YbB6 powder is 10-50 μm.

[0041] Controlling the raw materials within the above-mentioned particle size range can effectively ensure that Ti powder, Al powder and YbB6 powder can react completely during the sintering process, wherein the Yb in YbB6 can absorb as much residual oxygen in the matrix as possible and generate an appropriate amount of dispersed second phase TiB, effectively improving the mechanical properties of the prepared titanium aluminum alloy.

[0042] In some embodiments of the present application, the mixing step includes ball milling. Ball milling is used to mix the raw materials on the one hand, and to perform initial partial alloying of Ti and Al on the premise of uniform mixing on the other hand.

[0043] In some embodiments of the present application, the ball milling mixing satisfies at least one of the following items ①-②:

[0044] ① The grinding balls of the ball mill are composed of 15mm, 10mm and 5mm in diameter in a mass ratio of 3-5:3-5:2;

[0045] ② The ball-to-material ratio of the ball mill is (10-15):1, the filling coefficient of the ball mill jar is 0.4-0.5, the ball mill speed is 200-400r / min, and the ball mill time is 10-12h.

[0046] In some preferred embodiments, the steel grinding balls are composed of 15 mm, 10 mm and 5 mm diameters in a mass ratio of 4:4:2, the ball mill is made of stainless steel, and two exhaust valves are provided on the end cover of the ball mill, which are successively connected to a mechanical pump to evacuate and introduce protective gas to form a protective atmosphere, and finally the protective gas pressure in the tank is maintained at a level equivalent to atmospheric pressure. The ball-to-material ratio of the ball mill is preferably 10:1, the ball mill speed is preferably 300 r / min, and the ball mill time is preferably 4 hours.

[0047] In some embodiments of the present application, the materials are mixed without balls after the ball milling, and at least one of the following items ①-② is satisfied;

[0048] ① The ball-milled material is mixed in a three-dimensional mixer without balls, the mixing speed is 30-40 rpm, and the mixing time is 12-24 hours;

[0049] ② After the ball milling, ball-free mixing is performed, and the ball milling and / or ball-free mixing is performed under protective gas conditions.

[0050] In some embodiments, the ball-milled powder is taken out in a glove box filled with protective gas. The ball-milled powder is then mixed in a three-dimensional mixer without balls and protected by high-purity protective gas to avoid oxidation of the material by oxygen, reduce sintering defects, and achieve high density. Powder mixing is carried out on a three-dimensional mixer, and the mixing speed is 30rpm and the mixing time is 12h. By using ball milling and mechanical powder mixing in combination, the homogenization of the mixed powder can be ensured, and the added YbB6 powder, titanium powder and aluminum powder are evenly distributed, which is more conducive to the homogenization of the composition of the sintered product, which can not only improve the density and reduce defects of the titanium aluminum alloy, but also improve the strength and toughness. In some preferred embodiments, the protective gas is high-purity Ar gas.

[0051] In some embodiments of the present application, the sintering is performed in a spark plasma sintering furnace.

[0052] In some embodiments of the present application, the sintering satisfies at least one of the following items ①-④;

[0053] ① The sintering is performed by loading the mixed raw materials into a graphite mold and then performing the sintering in a spark plasma sintering furnace. The ratio of the height of the graphite mold to the height of the loaded materials is 1:0.4-0.6. In some embodiments, the graphite mold is 30 mm in diameter, and the amount of the mixed powder added to the mold is 25 g.

[0054] ② During the sintering, the spark plasma sintering furnace pressure is less than 1×10 -2 Pa, in a vacuum state, the titanium-aluminum alloy powder is prevented from being oxidized during the sintering process. Controlling the vacuum degree within this range can not only prevent the titanium-aluminum alloy powder from being oxidized during the sintering process, but also effectively ensure the normal sintering work, the sintering efficiency and the quality of the sintered product.

[0055] ③ The sintering temperature is 1100-1300℃; the sintering holding time is 5-10min; the sintering pressure is 30-40MPa; the sintering rate is 100-120℃ / min;

[0056] ④ The sintering temperature is 1200℃; the sintering holding time is 5min; the sintering pressure is 40MPa; and the sintering rate is 120℃ / min.

[0057] The purpose of adopting the above-mentioned sintering temperature is to effectively control the sintering temperature. If the sintering temperature is lower than 1200°C, the sintered product cannot be completely dense and contains many pores and holes, which affect the mechanical properties. When the sintering temperature is higher than 1200°C, the density and performance of the sintered product are not much different from those sintered at 1200°C. Therefore, in order to save energy and improve the performance of the composite material, the sintering temperature is set to 1200°C.

[0058] Through the setting of the above steps and the selection of parameters, the prepared titanium aluminum alloy has the advantages of fine grain size and high density, and the density is above 99%. At the same time, the titanium aluminum alloy prepared by the above method also has the advantages of high hardness, high tensile strength and good toughness.

[0059] In order to further illustrate the technical effects of the present invention, the present invention is described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0060] Example 1

[0061] This embodiment provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0062] S1: Ti powder with a particle size of 30-70 μm, Al powder with a particle size of 20-50 μm and YbB6 powder with a particle size of 10-50 μm were prepared in a mass ratio of 54.7:44.8:0.5, the ball-to-material ratio during ball milling was 10:1, the filling coefficient was 0.4, the rotation speed was 300 r / min, the ball milling time was 4 h, and then mixed at a speed of 30 rpm for 12 h on a three-dimensional mixer to obtain a mixed powder. The entire powder mixing process was operated in a high-purity argon atmosphere;

[0063] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0064] S3: Sintering treatment is performed, and the sintering heating rate is 110°C / min, the sintering pressure is 40MPa, the sintering temperature is 1100°C, and the temperature is kept for 10 minutes, and then cooled to room temperature with the furnace to obtain high-performance Ti-45Al titanium-aluminum alloy.

[0065] Example 2

[0066] This embodiment provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0067] S1: Ti powder with a particle size of 30-70 μm, Al powder with a particle size of 20-50 μm and YbB6 powder with a particle size of 10-50 μm are prepared in a mass ratio of 54.9:44.9:0.2, the ball-to-material ratio during ball milling is 15:1, the filling coefficient is 0.4, the rotation speed is 400 r / min, the ball milling time is 5 h, and then mixed at a speed of 35 rpm for 24 h on a mixer to obtain a mixture, and the entire powder mixing step is carried out in an argon protective atmosphere;

[0068] S2: Weigh 25 g of the mixed powder into a graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0069] S3: Sintering treatment is performed, and the sintering heating rate is 130°C / min, the sintering pressure is 30MPa, the sintering temperature is 1300°C, and the temperature is kept for 5 minutes, and then cooled to room temperature with the furnace to obtain a high-performance Ti-45Al titanium-aluminum alloy.

[0070] Example 3

[0071] This embodiment provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0072] S1: Ti powder with a particle size of 30-70 μm, Al powder with a particle size of 20-50 μm and YbB6 powder with a particle size of 10-50 μm are prepared in a mass ratio of 54.8:44.9:0.3, the ball-to-material ratio during ball milling is 10:1, the filling coefficient is 0.5, the rotation speed is 300 r / min, the ball milling time is 4 h, and then mixed at a speed of 30 rpm for 12 h on a three-dimensional mixer to obtain a mixture, and the entire powder mixing step is carried out in an argon protective atmosphere;

[0073] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0074] S3: Sintering treatment is performed, and the sintering heating rate is 120°C / min, the sintering pressure is 40MPa, the sintering temperature is 1200°C, and the temperature is kept for 5 minutes, and then cooled to room temperature with the furnace to obtain a fine-grained and high-density Ti-45Al titanium-aluminum alloy.

[0075] Example 4

[0076] This embodiment provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0077] S1: Ti powder with a particle size of 30-70 μm, Al powder with a particle size of 20-50 μm and YbB6 powder with a particle size of 10-50 μm are prepared in a mass ratio of 54.8:44.8:0.4, the ball-to-material ratio during ball milling is 13:1, the filling coefficient is 0.5, the rotation speed is 400 r / min, the ball milling time is 3 h, and then mixed at a speed of 40 rpm for 12 h on a three-dimensional mixer to obtain a mixture, and the entire powder mixing step is carried out in an argon protective atmosphere;

[0078] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0079] S3: Sintering treatment is performed, and the sintering heating rate is 120°C / min, the sintering pressure is 40MPa, the sintering temperature is 1200°C, and the temperature is kept for 10 minutes, and then cooled to room temperature with the furnace to obtain a fine-grained and high-density Ti-45Al titanium-aluminum alloy.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0082] S1: Ti powder with a particle size of 30-70 μm, Al powder with a particle size of 20-50 μm and YbB6 powder with a particle size of 10-50 μm were mixed in a mass ratio of 55:45:0, the ball-to-material ratio was 10:1 during ball milling, the ball milling time was 4 h, the filling coefficient was 0.4, the rotation speed was 250 r / min, and then mixed in a three-dimensional mixer at a speed of 30 rpm for 12 h to obtain a mixture, and the entire powder mixing step was not performed with atmosphere protection;

[0083] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0084] S3: Sintering treatment is performed, and the sintering heating rate is 120°C / min, the sintering pressure is 40MPa, the sintering temperature is 1200°C, and the temperature is kept for 5 minutes, and then cooled to room temperature with the furnace to obtain a fine-grained and high-density Ti-45Al titanium-aluminum alloy.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0087] S1: Ti powder with a particle size of 30-70 μm, Al powder with a particle size of 20-50 μm and YbB6 powder with a particle size of 10-50 μm were prepared in a mass ratio of 54.8:44.9:0.3, the ball-to-material ratio during ball milling was 15:1, the filling coefficient was 0.4, the rotation speed was 350 r / min, the ball milling time was 4 h, and then mixed at a speed of 30 rpm for 12 h on a three-dimensional mixer to obtain a mixture, and the entire powder mixing process was operated in a high-purity argon atmosphere;

[0088] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0089] S3: Sintering treatment is performed, and the sintering heating rate is 120°C / min, the sintering pressure is 40MPa, the sintering temperature is 1200°C, and the temperature is kept for 5 minutes, and then cooled to room temperature with the furnace to obtain a fine-grained and high-density Ti-45Al titanium-aluminum alloy.

[0090] Comparative Example 3

[0091] This comparative example provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0092] S1: Ti powder with a particle size of 30-70 μm, Al powder with a particle size of 20-50 μm and YbB6 powder with a particle size of 10-50 μm were prepared in a mass ratio of 54.8:44.8:0.4, the ball-to-material ratio during ball milling was 13:1, the filling coefficient was 0.4, the rotation speed was 300 r / min, the ball milling time was 3 h, and then mixed at a speed of 30 rpm for 20 h on a three-dimensional mixer to obtain a mixture;

[0093] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0094] S3: Sintering treatment is performed, and the sintering heating rate is 120°C / min, the sintering pressure is 40MPa, the sintering temperature is 1200°C, and the temperature is kept for 5 minutes, and then cooled to room temperature with the furnace to obtain a fine-grained and high-density Ti-45Al titanium-aluminum alloy.

[0095] Comparative Example 4

[0096] This comparative example provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0097] S1: Ti powder with a particle size of 30-70 μm, Al powder with a particle size of 20-50 μm and YbB6 powder with a particle size of 10-50 μm are prepared in a mass ratio of 54.8:44.8:0.4, and mixed on a three-dimensional mixer at a speed of 40 rpm for 12 h to obtain a mixture. The entire powder mixing step is carried out in an argon protective atmosphere;

[0098] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0099] S3: Sintering treatment is performed, and the sintering heating rate is 120°C / min, the sintering pressure is 40MPa, the sintering temperature is 1200°C, and the temperature is kept for 10 minutes, and then cooled to room temperature with the furnace to obtain a fine-grained and high-density Ti-45Al titanium-aluminum alloy.

[0100] Comparative Example 5

[0101] This comparative example provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0102] S1: Ti powder with a particle size of 10-20 μm, Al powder with a particle size of 5-10 μm and YbB6 powder with a particle size of 3-10 μm are prepared in a mass ratio of 54.8:44.8:0.4, the ball-to-material ratio during ball milling is 13:1, the filling coefficient is 0.5, the rotation speed is 400 r / min, the ball milling time is 3 h, and then mixed at a speed of 40 rpm for 12 h on a three-dimensional mixer to obtain a mixture, and the entire powder mixing step is carried out in an argon protective atmosphere;

[0103] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0104] S3: Sintering treatment is performed, and the sintering heating rate is 120°C / min, the sintering pressure is 40MPa, the sintering temperature is 1200°C, and the temperature is kept for 10 minutes, and then cooled to room temperature with the furnace to obtain a fine-grained and high-density Ti-45Al titanium-aluminum alloy.

[0105] Comparative Example 6

[0106] This comparative example provides a method for preparing a fine-grained high-density titanium-aluminum alloy, which is prepared by the following method:

[0107] S1: Ti powder with a particle size of 100-150 μm, Al powder with a particle size of 70-90 μm and YbB6 powder with a particle size of 70-90 μm were prepared in a mass ratio of 54.8:44.8:0.4, the ball-to-material ratio during ball milling was 13:1, the filling coefficient was 0.5, the rotation speed was 400 r / min, the ball milling time was 3 h, and then mixed at a speed of 40 rpm for 12 h on a three-dimensional mixer to obtain a mixture, and the entire powder mixing step was carried out in an argon protective atmosphere;

[0108] S2: Weigh 25g of the mixed powder into a high-strength graphite mold and place it in a spark plasma sintering furnace for sintering, and evacuate to 1×10 -2 Below Pa;

[0109] S3: Sintering treatment is performed, and the sintering heating rate is 120°C / min, the sintering pressure is 40MPa, the sintering temperature is 1200°C, and the temperature is kept for 10 minutes, and then cooled to room temperature with the furnace to obtain a fine-grained and high-density Ti-45Al titanium-aluminum alloy.

[0110] Experimental Example 1

[0111] The density of fine-grained and high-density Ti-45Al titanium-aluminum alloy was tested by the Archimedes drainage method. The test results are shown in Table 1.

[0112] Table 1 Density and grain size test results of Ti-45Al titanium-aluminum alloy composites

[0113] serial number Grain size (μm) <![CDATA[Density (g / cm 3 )]]> Density(%) Example 1 3.60 3.898 98.53 Example 2 3.08 3.947 99.77 Example 3 2.23 3.943 99.67 Example 4 3.35 3.929 99.32 Comparative Example 1 8.28 3.865 97.69 Comparative Example 2 6.05 3.897 98.51 Comparative Example 3 5.80 3.672 92.83 Comparative Example 4 11.2 3.543 89.56 Comparative Example 5 8.37 3.660 92.52 Comparative Example 6 6.88 3.530 89.23

[0114] According to the data in Table 1 Figure 1 and Figure 2 It can be seen that the grain size of the fine-grained high-density spark plasma sintered titanium aluminum alloy prepared by the method and formula of the present invention has been significantly refined, and the density is high, indicating that the fine-grained high-density spark plasma sintered titanium aluminum alloy prepared by the present invention has a uniform distribution of components, and no more defects are generated, and can be used for the preparation of small precision machines. At the same time, according to the comparison between Examples 1, 2, 3, and 4 and Comparative Examples 1, 2, and 3, it can be seen that when the atomic ratio of Ti-45Al powder and YbB6 powder is 99.7:0.3, the sintering temperature is 1200°C, the sintering rate is 120°C / min, and the sintering pressure is 40MPa, the titanium aluminum alloy has a smaller grain size and a higher density; according to Example 4 compared with Comparative Examples 4, 5, and 6, it is shown that the raw material particle size and ball milling step have a significant improvement in the performance of the titanium aluminum alloy.

[0115] In summary, the embodiments of the present invention provide a fine-grained, high-density spark plasma sintered titanium-aluminum alloy and a preparation method thereof, and the prepared titanium-aluminum alloy has the advantages of fine grains and high density. Moreover, the preparation process is simple and convenient, and can be formed without post-processing, which reduces the production cost and improves the comprehensive mechanical properties of the sintered titanium-aluminum alloy.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a fine-grained, high-density titanium-aluminum alloy, characterized in that: The raw materials are mixed in proportion and sintered to obtain a fine-grained high-density titanium-aluminum alloy, wherein: The raw material consists of Ti powder, Al powder and YbB6 powder, wherein the particle size of the Ti powder is 30-70 μm; the particle size of the Al powder is 20-50 μm; the particle size of the YbB6 powder is 10-50 μm, and the mass fraction of YbB6 in the raw material is 0.2-0.5%; The mixing includes ball milling mixing, the ball-to-material ratio of the ball milling is 10-15:1, the filling coefficient of the ball milling jar is 0.4-0.5, the ball milling speed is 200-400r / min, and the ball milling time is 10-12h.

2. The method for preparing a fine-grained high-density titanium-aluminum alloy according to claim 1, characterized in that: The fine-grained high-density titanium-aluminum alloy comprises dispersed TiB and Yb2O3.

3. The method for preparing a fine-grained high-density titanium-aluminum alloy according to claim 1, characterized in that: The mass ratio of Ti powder to Al powder in the raw material is 50-60:40-50.

4. The method for preparing a fine-grained high-density titanium-aluminum alloy according to claim 1, characterized in that: The grinding balls of the ball mill are graded with diameters of 15 mm, 10 mm and 5 mm in a mass ratio of 3-5:3-5:

2.

5. The method for preparing a fine-grained high-density titanium-aluminum alloy according to claim 1, characterized in that: After the ball milling, the materials are mixed without balls, and at least one of the following items ①-② is met; ① The ball-milled materials are mixed in a three-dimensional mixer without balls, and the mixing speed is 30-40 rpm for 12-24 hours; ② After the ball milling, ball-free mixing is performed, and the ball milling and / or ball-free mixing is performed under protective gas conditions.

6. The method for preparing a fine-grained high-density titanium-aluminum alloy according to claim 1, characterized in that: The sintering is performed in a spark plasma sintering furnace.

7. The method for preparing a fine-grained high-density titanium-aluminum alloy according to claim 1, characterized in that: The sintering satisfies at least one of the following items ①-③; ① The sintering is to load the mixed raw materials into a graphite mold and then carry out the sintering in a spark plasma sintering furnace, and the ratio of the height of the graphite mold to the height of the loaded materials is 1:0.4-0.6; ② During the sintering, the spark plasma sintering furnace pressure is less than 1×10 -2 Pa; ③ The sintering temperature is 1100-1300℃; the sintering holding time is 5-10min; the sintering pressure is 30-40MPa; the sintering rate is 100-120℃ / min.

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