A TiVZrTaAl refractory high-entropy alloy and a preparation method thereof

Abstract

The present invention discloses a TiVZrTaAl refractory high-entropy alloy and a preparation method thereof, belonging to the technical field of alloy preparation. The refractory high-entropy alloy comprises the following components in atomic percentages: Ti 35-43%, V 24-28%, Zr 12-20%, Ta 12-20% and Al 5-15%. The TiVZrTaAl refractory high-entropy alloy prepared by the present invention has a BCC crystal structure, excellent compressive strength, good application potential, and its yield strength measured under room-temperature compression test is as high as about 1918 MPa; moreover, the method constructed by the present invention has a simple and feasible process flow.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy preparation, and particularly relates to a TiVZrTaAl refractory high-entropy alloy and a preparation method thereof. Background Art

[0002] High-entropy alloys are a new type of metallic material developed for high-performance materials to adapt to various harsh service environments. They are defined as alloys containing at least five different main elements, and the content of each main element is between 5-35 at%. High-entropy alloys themselves have high configurational entropy, which causes them to tend to form a single BCC or FCC phase, or a solid solution of BCC and FCC, thus avoiding the adverse factors brought about by the formation of intermetallic compounds. Due to the diverse composition elements and excellent properties of high-entropy alloys, it has greatly broadened the alloy design ideas of people, and has been applied in the fields of aerospace and so on.

[0003] Refractory high-entropy alloys are alloy materials further developed on the basis of high-entropy alloys, and their main constituent elements are refractory elements. Refractory high-entropy alloys are prone to becoming brittle at room temperature or low temperature and have oxidation sensitivity. In order to further improve the mechanical properties of high-entropy alloys and obtain new alloy materials with high strength-ductility trade-off, the research focus in recent years has been on exploring the influence of chemical inhomogeneity on alloy properties. Improving properties through alloy design and effective composition search strategies, such as short-range order and local chemical fluctuations, is a method worth trying to achieve the synergistic combination of ultra-high strength and ductility of refractory high-entropy alloys. Summary of the Invention

[0004] Aiming at the above deficiencies in the prior art, the present invention provides a TiVZrTaAl refractory high-entropy alloy and a preparation method thereof. Based on the design concept of negative enthalpy solid solution, the present invention adds Al element that can reduce the mixing enthalpy of the system to the alloy to obtain a new alloy with high compressive strength.

[0005] To achieve the above object, the technical solution adopted by the present invention to solve its technical problems is:

[0006] A TiVZrTaAl refractory high-entropy alloy, which comprises the following components in atomic percentage:

[0007] Ti 35~43%, V 24~28%, Zr 12~20%, Ta 12~20% and Al 5~15%.

[0008] Further, in atomic percentage, it comprises the following components:

[0009] Ti 35~40%, V 24~25%, Zr 12~15%, Ta 12~15% and Al 5~10%.

[0010] Further, in atomic percentage, the TiVZrTaAl refractory high-entropy alloy is Ti 36.9 V 24.3 Zr 14.4 Ta 14.4 Al 10 .

[0011] Further, the TiVZrTaAl refractory high-entropy alloy has a BCC crystal structure.

[0012] A method for preparing the above-mentioned TiVZrTaAl refractory high-entropy alloy includes the following steps:

[0013] (1) Weigh Ti powder, V powder, Zr powder, Ta powder and Al powder in proportion, and then carry out sealed melting in the order of decreasing melting point;

[0014] (2) After melting, evacuate, then introduce an inert gas for gas washing, and then repeat evacuation and turn on the water circulation;

[0015] (3) Carry out arc melting. After complete melting, keep the arc on, then carry out exhaust treatment, and obtain an alloy sample after cooling;

[0016] (4) Repeat the process described in step (3) 8 to 10 times, and prepare the TiVZrTaAl refractory high-entropy alloy after cooling.

[0017] Further, the purity of the powder used in step (1) is 99.9 wt%.

[0018] Further, in the melting process of step (1), zinc blocks are also required to absorb the residual air.

[0019] Further, the specific process of arc melting in step (3) is as follows:

[0020] Gently touch the tungsten electrode tip on the surface of the zinc block and quickly lift it to start arc melting, so that the preset zinc blocks consume the residual air in the chamber; then start melting the alloy, and during the melting process, electromagnetic stirring is supplemented from time to time to make the raw materials mix more evenly; after the alloy is completely melted, keep the arc on for 3 min, and at the same time carry out electromagnetic stirring to fully discharge the residual gas in the alloy liquid; finally, control the alloy to cool slowly with the furnace to room temperature to obtain the alloy sample.

[0021] Advantages of the present invention:

[0022] The TiVZrTaAl refractory high-entropy alloy prepared by the present invention has a BCC crystal structure, has excellent compressive strength, good application potential, and its yield strength measured under room temperature compression test is as high as about 1918 MPa; and the method constructed by the present invention has a simple and feasible process flow. Description of the Drawings

[0023] Figure 1 X-ray diffraction patterns of the TiVZrTaAl refractory high-entropy alloy prepared according to the present invention and the TiVZrTa high-entropy alloy prepared in the comparative example;

[0024] Figure 2 X-ray diffraction patterns of the TiVZrTaO high-entropy alloy and the TiTaZrNb high-entropy alloy prepared in the comparative example;

[0025] Figure 3 Room temperature compression property curve of the TiVZrTa high-entropy alloy prepared in the comparative example;

[0026] Figure 4 Room temperature compression property curve of the TiVZrTaO high-entropy alloy prepared in the comparative example;

[0027] Figure 5 Room temperature compression property curve of the TiTaZrNb high-entropy alloy prepared in the comparative example;

[0028] Figure 6 Room temperature compression property curve of the TiVZrTaAl high-entropy alloy prepared according to the present invention. Detailed Description of the Invention

[0029] The following is a description of the specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

[0030] Example 1

[0031] A TiVZrTaAl refractory high-entropy alloy is prepared as follows:

[0032] (1) The refractory high-entropy alloy is composed of Ti, V, Zr, Ta, and Al elements and is designed to maintain a low or even negative mixing enthalpy. By atomic percentage, the content of each component is: (Ti 41 V 27 Zr 16 Ta 16 ) 90 Al 10 , and the equivalent mass ratio is Ti 24.6 V 17.2 Zr 18.3 Ta 36.2 Al 3.7; Then, precisely weigh high-purity (99.9 wt%) metal particles: 24.6 g of Ti, 2.7 g of V, 18.3 g of Zr, 36.2 g of Ta, and 3.7 g of Al using an electronic balance;

[0033] (2) Conduct alloy melting using a non-consumable high-vacuum arc melting furnace. Place the weighed metal particles from step (1) in a water-cooled copper crucible in the melting furnace cavity in ascending order of melting point. Additionally, place a zinc block elsewhere in the chamber to further absorb the residual air in the chamber; then close the melting furnace and tighten the sealing knobs around the sample chamber;

[0034] (3) Turn on the mechanical pump to evacuate the air, and wait for about 15 min; at this time, check the reading of the molecular pump tracker. When it shows 36000, turn off the mechanical pump and turn on the molecular pump to further evacuate the air finely, and wait for about 15 min as well;

[0035] (4) Conduct gas washing with argon. Open the valve until the pressure gauge shows 0; then repeat step (3) to evacuate the air. The purpose of this step is to maintain an inert environment in the melting furnace to prevent the sample from being oxidized at high temperatures; then turn on the water circulation cooling system;

[0036] (5) Start arc melting: Adjust the current knob to control the current between 60 - 100 A. Touch the tungsten electrode tip gently on the surface of the zinc block and quickly lift it to start the arc. The melting time is 1 min to consume the residual air in the chamber with the preset zinc block; then start melting the alloy. The operation method is the same as above. During the melting process, supplement with electromagnetic stirring from time to time to make the raw materials mix more evenly; after the alloy is completely melted, keep the arc for 3 min while conducting electromagnetic stirring to fully discharge the residual gas in the alloy liquid; finally, control the alloy to cool slowly with the furnace to room temperature to obtain the alloy sample;

[0037] (6) Repeat step (5) to remelt the alloy sample 8 - 10 times to make the sample composition more uniform; cool slowly with the furnace to obtain the refractory high-entropy alloy TiVZrTaAl.

[0038] Comparative Example

[0039] 1. This comparative example is a refractory high-entropy alloy of TiVZrTa. Prepare a refractory high-entropy alloy with an atomic ratio of Ti 41 V 27 Zr 16 Ta 16 according to the process flow of Example 1.

[0040] 2. This comparative example is a refractory high-entropy alloy of TiVZrTaO. Prepare a refractory high-entropy alloy with an atomic ratio of (TiVZrTa)O 10A refractory high-entropy alloy, and the crystal structure, mechanical properties, etc. of this comparative alloy were tested and analyzed.

[0041] 3. This comparative example is a TiTaZrNb refractory high-entropy alloy, and an alloy with an atomic ratio of Ti 41 Ta 27 Zr 16 Nb 16 was prepared according to the process flow of Example 1, and the crystal structure, mechanical properties, etc. of this comparative alloy were tested and analyzed.

[0042] Test Example

[0043] 1. Test the structures of the TiVZrTaAl refractory high-entropy alloy prepared by the present invention and the alloys prepared in each comparative example

[0044] The alloys prepared in the examples and comparative examples were subjected to phase analysis. X-ray diffraction analysis was carried out using a Rigaku D / Max2500 X-ray diffractometer from Rigaku, Japan. The technical specifications of the equipment are: Cu radiation source, graphite monochromator, operating voltage 40 kV, current 250 mA, rotating anode; scanning rate is 10° / min, diffraction angle range is 10 - 90°, and the results are shown in Figure 1 .

[0045] As Figure 1 shown, the X-ray diffraction results show that the TiVZrTaAl refractory high-entropy alloy prepared by the present invention has a BCC structure, while the alloys prepared in the comparative examples do not have a BCC structure ( Figure 2 ).

[0046] 2. Test the room-temperature compression performance of the TiVZrTaAl refractory high-entropy alloy

[0047] The detection was carried out using a compression test method. The specific process is as follows:

[0048] Compression specimens were cut out using a wire electrical discharge machining (WEDM) machine tool. The specimens were cylinders with a diameter of 4 mm and a height of 8 mm, and the upper and lower surfaces were kept flat; a universal testing machine was used for room-temperature compression tests, and a constant compression rate of 0.48 mm / min was set, corresponding to an initial strain rate of 10 -3 s -1 . The test results are shown in Figures 3 to 6 .

[0049] As Figures 3 to 6 shown, the compressive strength of the TiVZrTaAl refractory high-entropy alloy prepared by the present invention can reach 1918 MPa ( Figure 6 ), and it is brittle failure. Compared with the comparative alloy, there is a significant improvement in strength.

[0050] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A TiVZrTaAl refractory high-entropy alloy, characterized in that, Composed of the following components by atomic percentage: Ti 35 - 43%, V 24 - 28%, Zr 12 - 20%, Ta 12 - 20% and Al 5 - 15%.

2. The TiVZrTaAl refractory high-entropy alloy according to claim 1, characterized in that, Composed of the following components by atomic percentage: Ti 35 - 40%, V 24 - 25%, Zr 12 - 15%, Ta 12 - 15% and Al 5 - 10%.

3. The TiVZrTaAl refractory high-entropy alloy according to claim 1 or 2, characterized in that In atomic percentage, the TiVZrTaAl refractory high-entropy alloy is Ti 36.9 V 24.3 Zr 14.4 Ta 14.4 Al 10 .

4. The TiVZrTaAl refractory high-entropy alloy according to claim 3, characterized in that, The TiVZrTaAl refractory high-entropy alloy has a BCC crystal structure.

5. A method for preparing the TiVZrTaAl refractory high-entropy alloy according to any one of claims 1 to 4, characterized in that, Including the following steps: (1) Weigh Ti powder, V powder, Zr powder, Ta powder and Al powder in proportion, and then carry out sealed melting in the order of decreasing melting point; (2) After melting, evacuate the vacuum, then introduce inert gas for gas washing, and then repeat evacuating the vacuum and turn on the water circulation; (3) Carry out arc melting. After complete melting, keep the arc on, then carry out exhaust treatment, and obtain an alloy sample after cooling; (4) Repeat the process of step (3) 8 - 10 times, and obtain the TiVZrTaAl refractory high-entropy alloy after cooling.

6. The method according to claim 5, wherein The purity of the powder used in step (1) is 99.9wt%.

7. The method according to claim 5, characterized in that, In step (1), residual air needs to be removed during the melting process.

8. The method according to claim 5, wherein The specific process of arc melting in step (3) is as follows: Touch the tungsten electrode tip on the surface of the zinc block and then lift it to start arc melting, so that the preset zinc block consumes the residual air in the chamber; then start melting the alloy; after the alloy is completely melted, keep the arc on for 3 min, while carrying out electromagnetic stirring to discharge the residual gas; finally, control the alloy to cool to room temperature with the furnace to obtain an alloy sample.

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