A bulk dual-phase high-entropy alloy and a preparation method thereof

Abstract

The present invention discloses a bulk dual-phase high-entropy alloy and a preparation method thereof, aiming to solve the technical problems of easy deformation and low strength of traditional alloy materials in high-temperature environments. The technical solution is as follows: The expression of the dual-phase high-entropy alloy of the present invention is Cr a Fe b Hf c Mn d Ti e V f , where a + b + c + d + e + f = 100, a = 15 - 17, b = 15 - 17, c = 15 - 17, d = 15 - 17, e = 15 - 17, f = 15 - 17. The alloy of the present invention has a composite structure combining a solid solution phase and a Laves phase, has a relatively high as-cast hardness value, has good high-temperature stability, and can still maintain good hardness after high-temperature annealing, overcoming the high-temperature softening problem that is difficult to solve with traditional alloys.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallic materials, and particularly relates to a bulk dual-phase high-entropy alloy and a preparation method thereof. Background Art

[0002] With the development of current industrial technologies, the service temperature requirements for components are getting higher and higher. For example, the hot-end components of modern aviation and aerospace engines, such as combustion chambers, turbine blades, etc.; and in the industrial sectors of petrochemical, power, automotive, nuclear energy, etc. in the energy field, such as industrial gas turbines, steam turbines, vehicle turbochargers, petrochemical energy conversion devices, etc. These application requirements demand that the materials used for components have excellent high-temperature strength and good comprehensive mechanical properties such as fatigue performance and fracture toughness. Among them, high-temperature softening has always been a bottleneck problem restricting the high-temperature mechanical properties of traditional alloy materials and restricting the application of alloy materials in high-temperature components.

[0003] High-entropy alloys are a new type of alloy material proposed at the beginning of this century, generally alloyed by four or more elements in equiatomic ratio or near equiatomic ratio. The thermodynamic characteristics such as high configurational entropy of high-entropy alloys endow them with excellent thermal stability and high-temperature mechanical properties, and can effectively overcome the disadvantages of traditional alloys such as easy deformation and low strength at high temperatures. Summary of the Invention

[0004] The purpose of the present invention is to provide a bulk dual-phase high-entropy alloy and a preparation method thereof to solve the above technical problems.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions to achieve:

[0006] A bulk dual-phase high-entropy alloy, whose alloy expression is Cr a Fe b Hf c Mn d Ti e V f , where: a + b + c + d + e + f = 100, a = 15 - 17, b = 15 - 17, c = 15 - 17, d = 15 - 17, e = 15 - 17, f = 15 - 17, and the structure of the dual-phase high-entropy alloy is composed of a Laves phase and a body-centered cubic high-entropy solid solution phase.

[0007] A preparation method of a bulk dual-phase high-entropy alloy, comprising the following steps:

[0008] Step 1: Weigh the components of Cr, Fe, Hf, Mn, Ti, and V according to the atomic mole percentages,

[0009] Cr 15 - 17%; Fe 15 - 17%; Hf 15 - 17%; Mn 15 - 17%; Ti 15 - 17%;

[0010] V 15 - 17%;

[0011] All of the above raw materials are pure metal sheets or cylindrical particles with a purity greater than 99.5%;

[0012] Step 2: Place the above raw materials in a water-cooled copper crucible and melt them under a high vacuum and in an inert gas protection environment;

[0013] Step 3: Shape the alloy liquid obtained after uniform melting to obtain the bulk dual-phase high-entropy alloy.

[0014] Preferably, the melting time in Step 2 is 5 - 10 minutes, and this melting process needs to be repeated 4 - 5 times; after each melting, turn over the obtained ingot.

[0015] Preferably, the melting method in Step 2 is any one of arc melting or induction melting.

[0016] Preferably, the inert gas in Step 2 is argon.

[0017] Preferably, the shaping method in Step 3 is casting or suction casting.

[0018] The beneficial effects of the present invention are:

[0019] 1. The present invention has a composite structure combining a solid solution phase and a Laves phase, and has a relatively high as-cast hardness value;

[0020] 2. The present invention has good high-temperature stability and can still maintain good hardness after high-temperature annealing, overcoming the high-temperature softening problem that traditional alloys are difficult to solve;

[0021] 3. The present invention can be prepared by arc or induction melting methods, with simple processes, short preparation processes, and high production efficiency. Description of the Drawings

[0022] Figure 1 It is a metallographic structure photograph of the high-entropy alloy in Example 1, where the white part is the solid solution phase and the black part is the void left after the brittle Laves phase is removed during the polishing process;

[0023] Figure 2 It is the X-ray diffraction pattern of the Cr-Fe-Hf-Mn-Ti-V high-entropy alloy obtained in Example 1 of the present invention;

[0024] Figure 3 It is the Vickers hardness diagram of the Cr-Fe-Hf-Mn-Ti-V high-entropy alloy obtained in Example 1 of the present invention;

[0025] Figure 4 Vickers hardness diagram of the Cr-Fe-Hf-Mn-Ti-V high-entropy alloy obtained in Example 1 of the present invention after annealing at 900 °C for 8 hours. Detailed implementation manners

[0026] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments and drawings. However, the following embodiments are only the preferred embodiments of the present invention, not all of them. Based on the embodiments in the implementation manners, other embodiments obtained by those skilled in the art without creative efforts all belong to the protection scope of the present invention.

[0027] The specific embodiments of the present invention will be described below with reference to the drawings.

[0028] Example 1

[0029] A bulk dual-phase high-entropy alloy, the alloy expression of which is Cr 16 Fe 16 Hf 16 Mn 16 Ti 16 V 16 , and the alloy structure is composed of a Laves phase and a body-centered cubic high-entropy solid solution phase.

[0030] The preparation steps are as follows:

[0031] Charge the raw materials of Cr, Fe, Hf, Mn, V, and Ti with a purity greater than 99.9% according to the atomic molar percentages shown in the expression, and put them into the copper crucible of the arc furnace in order of increasing melting point. After the mechanical vacuum pump evacuates to 0.1 Pa, use the molecular pump to continue evacuating to 5.5×10 -3 Pa, and then fill argon to 0.1 Pa. Repeat the evacuation and argon filling 2 times, and start arc melting after the last argon filling. After arc ignition, gradually increase the current to 400 A and melt for 10 minutes until all the metal raw materials are completely melted. After turning the alloy ingot over, repeat this process 4 times and then carry out casting to obtain a dual-phase high-entropy alloy sample with uniform composition.

[0032] Example 2

[0033] A bulk dual-phase high-entropy alloy, the alloy expression of which is Cr 15 Fe 15 Hf 15 Mn 17 Ta 17 V 17 , and the alloy structure is composed of a Laves phase and a body-centered cubic high-entropy solid solution phase.

[0034] The preparation steps are as follows:

[0035] Charge the raw materials of Cr, Fe, Hf, Mn, V, and Ti with a purity greater than 99.5% according to the atomic molar percentages shown in the formula, and place them in the copper crucible of the electromagnetic induction furnace in ascending order of melting point. After evacuating to 0.1 Pa with a mechanical vacuum pump, continue to evacuate to 7.0×10 -3 Pa using a molecular pump, and then fill with argon to 0.1 Pa. Repeat the evacuation and argon filling 3 times, and turn on the power supply after the last argon filling. Gradually increase the power to kW and melt for 7 minutes until all the metal raw materials are completely melted. Repeat this process 5 times after turning the alloy ingot over, and then perform suction casting to obtain a duplex high-entropy alloy sample with uniform composition.

[0036] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A bulk dual-phase high-entropy alloy, characterized in that, Its alloy expression is Cr a Fe b Hf c Mn d Ti e V f , where: a + b + c + d + e + f = 100, a = 15 - 17, b = 15 - 17, c = 15 - 17, d = 15 - 17, e = 15 - 17, f = 15 - 17; the structure of the duplex high-entropy alloy consists of the Laves phase and the body-centered cubic high-entropy solid solution phase.

2. A method for preparing the bulk dual-phase high-entropy alloy according to claim 1, characterized in that, It includes the following steps: Step 1: Charge Cr, Fe, Hf, Mn, Ti, and V in the components according to the atomic mole percentage, Cr 15-17%; Fe 15-17%; Hf 15-17%; Mn 15-17%; Ti 15-17%; V 15~17％； All of the above raw materials are pure metal sheets or cylindrical particles with a purity greater than 99.5%; Step 2: Place the above raw materials in a water-cooled copper crucible and carry out melting under a high-vacuum and inert gas protection environment; Step 3: Shape the alloy liquid obtained after uniform melting to obtain the bulk dual-phase high-entropy alloy.

3. According to the method for preparing the bulk dual-phase high-entropy alloy according to claim 2, characterized in that: The melting time in Step 2 is 5-10 minutes, and this melting process needs to be repeated 4-5 times; turn over the obtained ingot after each melting.

4. According to the method for preparing the bulk dual-phase high-entropy alloy according to claim 2, characterized in that: The melting method in Step 2 adopts any one of arc melting or induction melting.

5. According to the method for preparing the bulk dual-phase high-entropy alloy according to claim 2, characterized in that: The inert gas in Step 2 is argon.

6. According to the method for preparing the bulk dual-phase high-entropy alloy according to claim 2, characterized in that: The shaping method in Step 3 is casting or suction casting.

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