Heat treatment method of crnifecutib high-strength and high-ductility high-entropy alloy, obtained material and application thereof

Abstract

The application belongs to the technical field of alloy process, and particularly relates to a heat treatment method of CrNiFeCuTiB high-strength and high-toughness high-entropy alloy, obtained material and application thereof. The heat treatment method is used to heat treat the CrNiFeCuTiB high-entropy alloy, so that the grain size of the CrNiFeCuTiB high-entropy alloy is finer than that in the as-cast state, the casting defects and holes are reduced, the structure is optimized, the mechanical properties are significantly improved, and the requirements of various extreme environments can be met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of alloy process, and particularly relates to a heat treatment method of CrNiFeCuTiB high-strength and high-toughness high-entropy alloy, obtained material and application thereof. BACKGROUND

[0002] High-entropy alloy is a multi-principal element alloy, which is usually composed of at least 5 elements, and the content of each element is between 5% and 35%. Due to the high-entropy effect of high-entropy alloy, the multi-principal element metal tends to form a simple solid solution rather than many complex phases. This effect enables high-entropy alloy to avoid the generation of brittle intermetallic compounds, and can have higher strength, better wear resistance and corrosion resistance, etc. The design concept of high-entropy alloy breaks through the limitation of traditional concept, has broad application prospect and promising development potential, and is a very new research hotspot in the field of material research at present. For example, CN110106457B discloses a high-entropy alloy impact heat treatment method, that is, during the heat treatment process of high-entropy alloy, dynamic impact force with adjustable energy and frequency parameters is applied to the alloy, and through the adjustment of various process parameters, the grain of high-entropy alloy is finally refined, the casting defects are eliminated, and the comprehensive performance of the material is improved.

[0003] The high-entropy alloy prepared by the casting method has the defects of coarse grain, composition segregation and many holes, so the as-cast high-entropy alloy has relatively poor plasticity, strength and strength. Based on this situation, in order to meet the performance and use requirements of aerospace, high temperature, strong oxidation and strong corrosion in special environment, it is of great significance to find a suitable heat treatment method for CrNiFeCuTiB high-strength and high-toughness high-entropy alloy. SUMMARY

[0004] In order to solve the problems of the prior art, the application provides a heat treatment method of CrNiFeCuTiB high-strength and high-toughness high-entropy alloy, obtained material and application thereof. Through the application, the defects of high-entropy alloy can be improved, the organization thereof can be optimized, and the mechanical properties thereof can be improved, so as to meet the needs of various extreme environments.

[0005] A heat treatment method of CrNiFeCuTiB high-strength and high-toughness high-entropy alloy, comprising the following steps:

[0006] 1) A CrNiFeCuTiB high-entropy alloy ingot is prepared by vacuum arc melting, and is polished and cut into a sample to be treated;

[0007] 2) The sample to be treated is placed in a tube furnace for heat treatment:

[0008] 2a) The tube furnace in which the sample to be treated is placed is provided with a protective gas condition;

[0009] 2b) heating the tube furnace to 600-800℃ at a rate of 4-7℃ / min and maintaining for 40-60 minutes;

[0010] 2c) heating the tube furnace to 1000-1100℃ at a rate of 10-20℃ / min and maintaining for 2-2.5 hours;

[0011] 2d) cooling the heat-treated sample to room temperature with the furnace, to obtain a CrNiFeCuTiB high-entropy alloy with high strength and toughness.

[0012] In the above technical solution:

[0013] The heat treatment of step 2b) can promote the phase transition of the solid solution to a stable phase, improve the internal structure of the alloy, and improve the mechanical properties of the alloy.

[0014] The heat treatment of step 2c) can increase the temperature, promote the rapid migration of atoms, accelerate the precipitation of the second phase, and simultaneously improve the solid solution strengthening and the second phase strengthening to improve the performance of the alloy.

[0015] The above heat treatment process can improve the defects of the CrNiFeCuTiB high-entropy alloy in the as-cast state, such as coarse grains, many pores, and segregation, to meet the needs of engineering practice.

[0016] Specifically, the CrNiFeCuTiB high-entropy alloy ingot is composed of Cr, Ni, Fe, Cu, Ti and B, wherein the atomic ratio of Cr:Ni:Fe:Cu:Ti:B is (0.1-1):(0.5-2):(0.5-1):(0.5-1.5):(0.1-0.5):(0.1-0.7), and the atomic ratio of (Ti+B) / (Cr+Ni+Fe+Cu) is 0.028≤(Ti+B) / (Cr+Ni+Fe+Cu)≤0.25.

[0017] Specifically, in step 2a), argon is passed at a flow rate of 15-20L / min for 3-5 minutes, and then argon is continuously passed at a flow rate of 5-8L / min until the end of the entire heat treatment process.

[0018] Further, the heat-treated CrNiFeCuTiB high-entropy alloy is ground and polished to form a metallographic sample, which can be used for subsequent observation of the alloy structure and mechanical property testing.

[0019] The application also provides a CrNiFeCuTiB high-entropy alloy with high strength and toughness obtained by the above heat treatment method.

[0020] The CrNiFeCuTiB high-entropy alloy provided by the application has a hardness of 850HV, a compressive strength of 2579MPa, and a compressive strain of 55.5%.

[0021] The application also provides application of the CrNiFeCuTiB high-strength and high-toughness high-entropy alloy.

[0022] The CrNiFeCuTiB high-strength and high-toughness high-entropy alloy is more suitable for being used as a wear-resistant material, a repair material or a structural material in the fields of aerospace, ship equipment, engineering machinery and bearing gears, and meets the requirements of use in extreme environments such as space and ocean.

[0023] The application has the following advantages:

[0024] The heat treatment method can make the grain size of the CrNiFeCuTiB high-entropy alloy finer, reduce casting defects and holes, optimize the structure and significantly improve the mechanical properties, so that the requirements of various extreme environments can be met. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The SEM image of the CrNiFeCuTiB high-strength and high-toughness high-entropy alloy before heat treatment.

[0026] Figure 2 The SEM image of the CrNiFeCuTiB high-strength and high-toughness high-entropy alloy after heat treatment according to the application. DETAILED DESCRIPTION

[0027] The principles and characteristics of the application are described below, and the examples are only used to explain the application and not to limit the scope of the application.

[0028] Preparation of the CrNiFeCuTiB high-entropy alloy ingot

[0029] Specific method:

[0030] 1) The clean Cr metal block, Ni metal block, Fe metal block, Cu metal block, Ti metal block and B particles are weighed according to the molar ratio of 0.5:1:0.7:1.1:0.3:0.2 for batching;

[0031] 2) The raw materials are placed in the copper crucible in the electric arc melting furnace, and the raw materials are arranged in the order of low melting point elements at the bottom and high melting point elements at the top;

[0032] 3) The vacuum degree in the electric arc melting furnace is adjusted to -0.1 MPa, and argon is used as the protective gas;

[0033] 4) Electric arc melting is performed to obtain the as-cast CrNiFeCuTiB high-strength and high-toughness high-entropy alloy.

[0034] Heat treatment of CrNiFeCuTiB high-entropy alloy ingot

[0035] The following methods were carried out on the process-specific parameters of the alloys of each example and comparative example in Table 1:

[0036] 1) The CrNiFeCuTiB high-entropy alloy ingot was polished and cut into a sample to be treated, and the heat-treated sample had a size of 10 mm * 10 mm * 30 mm;

[0037] 2) The sample to be treated was placed in a tube furnace for heat treatment:

[0038] 2a) The tube furnace in which the sample to be treated was placed was set to a protective gas condition;

[0039] 2b) The tube furnace was heated at a rate of 4-7 ℃ / min to 600-800 ℃ and held for 40-60 minutes;

[0040] 2c) The tube furnace was slowly heated at a rate of 10-20 ℃ / min to 1000-1100 ℃ and held for 2-2.5 hours;

[0041] 2d) The heat-treated sample was cooled to room temperature with the furnace, and a CrNiFeCuTiB high-entropy alloy with high strength and toughness was obtained.

[0042] The hardness, compressive strength, and compressive strain of each example and comparative example alloy were measured, and the results are shown in Table 2.

[0043] The hardness was measured using a Vickers hardness tester

[0044] The compressive strength and compressive strain were measured using a compressive strength tester.

[0045] Table 1 Process parameters of the alloys of each example and comparative example of the present application

[0046]

[0047] Table 2 Main mechanical property data of the alloys of each example and comparative example of the present application

[0048]

[0049] After heat treatment, as shown in Table 2, the hardness of the CrNiFeCuTiB high-entropy alloy with high strength and toughness was significantly improved compared to the comparative example and the as-cast alloy, and the compressive strength of the example was significantly improved compared to the comparative example while maintaining a high compressive strain. The alloy can be used as a repair material or structural material for aerospace and naval equipment, and is particularly suitable for use in extreme environments such as space or the ocean.

[0050] As shown in Figure 1 , it is a SEM diagram of CrNiFeCuTiB high strength and toughness high-entropy alloy before heat treatment.

[0051] As shown in Figure 2 , it is a SEM diagram of CrNiFeCuTiB high strength and toughness high-entropy alloy after heat treatment of the application.

[0052] According to Figure 1 and Figure 2 , it can be seen that after the heat treatment method of the application, the microstructure of CrNiFeCuTiB high strength and toughness high-entropy alloy has changed significantly, the alloy is composed of FCC phase as matrix and Laves and delta phase before heat treatment, after heat treatment, the dendritic structure is more developed, and the second phase precipitates more, which will make the hardness and strength of the alloy rise.

[0053] The above description is only the preferred embodiment of the application, and is not intended to limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A heat treatment method of a CrNiFeCuTiB system high strength and toughness high-entropy alloy, characterized by, The method comprises the following steps: 1) CrNiFeCuTiB high-entropy alloy ingot is prepared by vacuum induction melting, and the ingot is polished and cut into samples to be treated; 2) The samples to be treated are placed in a tube furnace for heat treatment: 2a) The tube furnace with the samples to be treated is set in a protective gas condition; 2b) The tube furnace is heated to 600-800℃ at a rate of 4-7℃ / min and kept for 40-60 minutes; 2c) The tube furnace is slowly heated to 1000-1100℃ at a rate of 10-20℃ / min and kept for 2-2.5 hours; 2d) The heat-treated samples are cooled to room temperature in the furnace to obtain CrNiFeCuTiB high-entropy alloy with high strength and toughness; The CrNiFeCuTiB high-entropy alloy ingot is composed of Cr, Ni, Fe, Cu, Ti and B, wherein the atomic ratio of Cr:Ni:Fe:Cu:Ti:B is (0.1-1):(0.5-2):(0.5-1):(0.5-1.5):(0.1-0.5): (0.1-0.7), and the atomic ratio of (Ti+B) / (Cr+Ni+Fe+Cu) is 0.028-0.

25. 2.The heat treatment method of CrNiFeCuTiB high strength and toughness high-entropy alloy according to claim 1, characterized in that: In step 2a), argon is introduced at a flow rate of 15-20 L / min for 3-5 minutes, and then continuously introduced at a flow rate of 5-8 L / min until the end of the whole heat treatment process.

3. A CrNiFeCuTiB high-entropy alloy with high strength and toughness obtained by the heat treatment method according to claim 1 or 2.

4. The use of the CrNiFeCuTiB high strength and toughness high-entropy alloy according to claim 3, characterized in that: The alloy is used for preparing wear-resistant materials, repair materials or structural materials in the fields of aerospace, marine equipment, engineering machinery or bearings and gears.

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