Large-size high-performance tantalum-tungsten-hafnium entropy control alloy capable of resisting high temperature of 2000 DEG C

Abstract

The invention discloses a large-size high-performance tantalum-tungsten-hafnium entropy-controlled alloy capable of resisting high temperature of 2000 DEG C. The alloy is composed of tantalum, tungsten, hafnium and carbon, and the component formula of the alloy is Ta1-x-y-zWxHfyCz, 8% < = x < = 20%, 2% < = y < = 10%, and 0.02% < = z < = 0.2%. The alloy not only has good plasticity at room temperature, can be used for forging and machining, but also has excellent obdurability at the ultrahigh temperature of 2000 DEG C, and is a candidate material for manufacturing hot end parts of aerospace crafts.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal materials, and particularly relates to a large-size high-performance tantalum-tungsten-hafnium entropy-controlled alloy resistant to 2000 DEG C high temperature. BACKGROUND

[0002] The service temperature of high-performance aircraft hot end components in the field of aerospace is as high as 2000 DEG C, which puts forward strict requirements on the high-temperature service performance of the manufacturing materials of the hot end components. Tantalum-tungsten refractory alloy, especially tantalum-tungsten-hafnium alloy, has excellent mechanical properties and processability, and is the preferred material for manufacturing hot end components of aircraft. For example, typical tantalum-tungsten-hafnium alloy T111 alloy and T222 alloy are the first developed tantalum-tungsten-hafnium alloy, and are widely used in the manufacturing of high-temperature hot end components. However, although T111 (Ta-8W-2Hf) alloy and T222 (Ta-10W-2.5Hf-0.01C) alloy have excellent plasticity and comprehensive mechanical properties at room temperature, their strength is still acceptable below 1800 DEG C, but their strength drops sharply when the service temperature exceeds 2000 DEG C, and they cannot meet the requirements of 2000 DEG C ultra-high temperature service environment. Although the introduction of C, B and other carbides can form a large amount of carbides in the tantalum-tungsten-hafnium refractory alloy, which can significantly improve the high-temperature strength of the alloy, the introduction of carbides makes the plasticity of the alloy drop sharply at room temperature, so that the alloy does not have processability and manufacturability, and it is also difficult to perform additive manufacturing 3D printing. Therefore, it is urgent to develop a new type of tantalum-tungsten-hafnium refractory alloy which has excellent plasticity at room temperature but still has high strength and toughness at 2000 DEG C ultra-high temperature. In addition, due to the high melting point of tantalum-tungsten refractory alloy, the current manufacturing of tantalum-tungsten-hafnium alloy mainly adopts electric arc melting process. On the one hand, the size of the manufactured alloy is relatively small, and on the other hand, element segregation and burning loss are prone to occur when manufacturing large-size alloy blocks. SUMMARY

[0003] The present application provides a large-size high-performance tantalum-tungsten-hafnium entropy-controlled alloy resistant to 2000 DEG C high temperature, which has excellent mechanical properties and processability at room temperature, and still has high mechanical strength at a high temperature of 2000 DEG C. In addition, a manufacturing method of large-size material of the tantalum-tungsten-hafnium entropy-controlled alloy is provided.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: a large-size regular billet entropy-controlled alloy is composed of tantalum, tungsten, hafnium and carbon elements, wherein tantalum, tungsten and hafnium are main elements, and the composition formula is Ta 1-x-y-z W x Hf y C z , wherein 8%≤x≤20%, 2%≤y≤10%, and 0.02%≤z≤0.2%.

[0005] The alloy preparation method and steps are as follows: According to the mass ratio, W powder, Ta powder, WC powder and Hf powder are taken, mechanical mixing powder is carried out in sequence, cold pressing into strip, vacuum sintering is carried out again, the vacuum sintering temperature is 1500-2000℃, the holding time is 1-10h, then repeated melting is carried out through the electron beam furnace, the electron beam melting passes through the steps of material preparation, preheating, melting, directional solidification, etc., the vacuum degree of the electron beam melting furnace is less than 5*10 - 2 Pa, and finally cast into shape to prepare a tantalum tungsten hafnium entropy control alloy;

[0006] In the step, the tantalum tungsten hafnium entropy control alloy is characterized in that, when the ingredients are used, Ta powder, W powder, Hf powder and WC powder are used, the purity is above 99.9wt%, and the particle size is 80-300 mesh.

[0007] In the step, the electron beam melting beam current is 100-400mA, and the melting time is 10-60min; after alloy melting, the electron beam current is gradually reduced to off.

[0008] In the step, the casting crucible is cylindrical, and the diameter is 80-200mm.

[0009] Compared with the prior art, the present application has the following beneficial effects: (1) The tantalum tungsten hafnium entropy control alloy prepared by the present application has uniform organization and stable structure, high yield strength and fracture strength and large elongation at a high temperature of up to 2000℃, and at the same time, it has excellent plasticity at room temperature, good processability, and performance significantly better than existing tantalum tungsten hafnium alloys; (2) The large size entropy control alloy provided by the present application can prepare large size block materials with a diameter of more than 80mm, and the block materials have uniform organization, accurate composition, can be subjected to subsequent forging and mechanical processing, and are suitable for manufacturing hot end parts with a service temperature of up to 2000℃; (3) The alloy composition is accurate, the process is simple, and the problem that traditional superhigh-temperature high-toughness refractory alloys cannot prepare large size accurate composition and uniform organization alloys is overcome, and high-performance raw materials are provided for the manufacturing of large size superhigh-temperature hot end parts; (4) The tantalum tungsten hafnium entropy control alloy has small element burning loss, uniform composition and large size specification, is suitable for forging and mechanical processing manufacturing, and can also be processed into powder and powder material for additive manufacturing 3D printing. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 Performance curves of the alloy at room temperature (a) and at a high temperature of 2000℃ (b) according to Example 1 Figure 2 Microscopic morphology diagram of the alloy according to Example 1 (a) and Example 2 (b) Figure 3 The room temperature performance curves of the alloys described in Comparative Example 1(a) and Comparative Example 2(b) are shown. Detailed Implementation Specific Implementation Example 1 A large-size, high-performance tantalum-tungsten-hafnium entropy-controlled alloy resistant to temperatures up to 2000℃, with the composition formula Ta 79.87 W 15.16 Hf 4.91 C 0.06 The alloy was prepared using the following process: W powder, Ta powder, WC powder, and Hf powder were prepared according to the specified mass ratio. The purity of the tantalum powder, tungsten powder, hafnium powder, and WC powder used in the batching was all above 99.9 wt%, and the particle size was 180 mesh. The powders were mechanically mixed, cold-pressed into strips, and vacuum-sintered at 1700℃ for 3 hours to obtain strip-shaped alloys. Then, electron beam melting was performed at a beam current of 320 mA for 30 minutes, repeated three times. After each alloy melting, the electron beam current was gradually reduced until it was turned off. Finally, the alloy was cast into a 100 mm diameter crucible to obtain an alloy ingot.

[0012] Alloy billets were prepared using the above method. Uniform samples were then taken and their mechanical properties were tested at room temperature and at an ultra-high temperature of 2000℃, as shown in the attached figures. Figure 1 As shown in (a) and (b), the prepared alloy exhibits excellent plasticity at room temperature, with a yield strength of 1453.38 MPa and a stress of 2252.40 MPa at a compression ratio of 37%. The alloy also demonstrates excellent strength and toughness at ultra-high temperatures of 2000℃, with a yield strength exceeding 130 MPa and a compression ratio greater than 30%. The microstructure and compositional distribution of the alloy were analyzed using scanning electron microscopy and energy dispersive spectroscopy, and the results are attached. Figure 2 (a) As shown, the alloy composition is accurate and the microstructure is uniform. Specific Implementation Example 2 A large-size, high-performance tantalum-tungsten-hafnium entropy-controlled alloy resistant to temperatures up to 2000℃, with the composition formula Ta 85.03 W 10.04 Hf 4.9 C 0.03 The alloy was prepared using the following process: W powder, Ta powder, WC powder, and Hf powder were prepared according to the specified mass ratio. The purity of the tantalum powder, tungsten powder, hafnium powder, and WC powder used in the batching was all above 99.9 wt%, and the particle size was 180 mesh. The powders were mechanically mixed, cold-pressed into strips, and vacuum-sintered at 1700℃ for 3 hours to obtain strip-shaped alloys. Then, electron beam melting was performed at a beam current of 300 mA for 25 minutes, repeated three times. After each alloy melting, the electron beam current was gradually reduced until it was turned off. Finally, the alloy was cast into an 80 mm diameter crucible to obtain an alloy ingot.

[0014] The alloy ingot is prepared by the above method, and a uniform texture sample is taken to perform compression performance test at room temperature and at 2000 DEG C ultra-high temperature, respectively. The prepared alloy has good plasticity at room temperature, the yield strength is 1005.94 MPa, and the stress reaches 1609.36 MPa when the compression rate is 40%. The alloy has excellent strength and toughness at 2000 DEG C ultra-high temperature, and the compression yield strength exceeds 100 MPa. The microstructure and composition distribution of the alloy are tested by a scanning electron microscope and an energy spectrum, and the results are shown in Figs. Figure 2 (b) and (b) show that the alloy composition is accurate, and the microstructure is uniform.

[0015] Comparative Example 1 A large-size refractory alloy has a composition formula of Ta 69.16 W 10.04 Hf 19.49 C 1.31 The same process as in Example 1 is adopted to prepare a block-shaped alloy. A uniform texture sample is taken to perform compression performance test at room temperature, and the results are shown in Fig. Figure 3 (a) shows that the prepared alloy has high strength at room temperature, but the alloy is brittle, the compression rate is less than 20%, and it is difficult to perform mechanical processing and additive manufacturing.

[0016] Comparative Example 2 A large-size refractory alloy has a composition formula of Ta 79.94 W 10.2 Hf 9.86 The same process as in Example 1 is adopted to prepare a block-shaped alloy. A uniform texture sample is taken to perform compression performance test at room temperature, and the results are shown in Fig. Figure 3 (b) shows that the prepared alloy has good plasticity at room temperature, but the strength at high temperature is low, and it cannot meet the service requirement of high-temperature strength of materials for aerospace hot-end components.

Claims

1. A large-size, high-performance tantalum-tungsten-hafnium entropy-controlled alloy resistant to 2000℃, composed of main elements Ta, W, Hf and trace amounts of C, with the following composition formula: Ta 1-x-y-z W x Hf y C z Where 8%≤x≤20%, 2%≤y≤10%, and 0.02%≤z≤0.2%.

2. The large-size, high-performance tantalum-tungsten-hafnium entropy-controlled alloy resistant to 2000℃ as described in claim 1 is prepared using the following process: According to the mass ratio, W powder, Ta powder, WC powder, and Hf powder are mechanically mixed and cold-pressed into strips, then vacuum sintered at a temperature of 1500℃ to 2000℃ for 1 to 10 hours. The resulting powders are then repeatedly melted in an electron beam furnace. The electron beam melting process includes material preparation, preheating, melting, and directional solidification. The vacuum degree of the electron beam melting furnace is less than 5 × 10⁻⁶. -2 Pa, and finally cast to obtain tantalum-tungsten-hafnium entropy-controlled alloy.

3. The tantalum-tungsten-hafnium entropy-controlled alloy as described in claim 2, characterized in that, The ingredients used in the formulation include Ta powder, W powder, Hf powder and WC powder, all with a purity of over 99.9 wt% and a particle size of 80-300 mesh.

4. The tantalum-tungsten-hafnium entropy-controlled alloy as described in claim 2, wherein the electron beam melting current is 100-400mA and the melting time is 10-60min; after the alloy is melted, the electron beam current is gradually reduced to the off state.

5. The tantalum-tungsten-hafnium entropy-controlled alloy as described in claim 2, wherein the casting crucible is cylindrical with a diameter of 80-200 mm.

6. The tantalum-tungsten-hafnium entropy-controlled alloy as described in claim 1 is used in the manufacture of ultra-high temperature structural components at 2000℃ in fields such as aviation, aerospace, and nuclear energy. It exhibits excellent strength and toughness at 2000℃ and good plasticity at room temperature.

7. The tantalum-tungsten-hafnium entropy-controlled alloy as described in claim 2 has uniform composition and large dimensions. It is suitable for subsequent forging and machining, and can be used to manufacture structural parts with service temperatures up to 2000°C. It can also be processed into powder for additive manufacturing and 3D printing.

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