Novel TiMnFeCoNi high-entropy shape memory alloy and preparation method thereof

Abstract

The invention discloses a preparation method of a novel high-entropy shape memory alloy, and belongs to the technical field of alloy materials. The alloy provided by the invention is the TiMnFeCoNi high-entropy shape memory alloy with the equal molar ratio, five elements are all 3d transition metal elements, the price is low, and the reserves are rich. The high-entropy shape memory alloy provided by the invention has an FCC and BCC dual-phase structure and a small amount of intermetallic compound precipitated phases, and can obtain good shape memory performance and superelasticity. The alloy prepared through spark plasma sintering is compact in structure, the subsequent heat treatment step is omitted, and the economical efficiency is high. Meanwhile, the hardness and compressive strength of the high-entropy shape memory alloy are 546 HV and 2131 MPa respectively, and the room-temperature compression shape memory recovery and the super-elastic recovery are 5.83% and 11.76% respectively.

Description

Technical Field

[0001] The invention relates to the technical field of metal functional materials, and in particular to a novel TiMnFeCoNi high-entropy shape memory alloy and a preparation method thereof. Background Art

[0002] The concept of high entropy shape memory alloy was first proposed by Firstov and others from the National Academy of Sciences of Ukraine in 2014. The original intention of the design was to solve the problem of alloy fatigue and memory performance degradation caused by irreversible plastic deformation in memory alloys. At present, high entropy shape memory alloys are all made by smelting methods. The directly obtained alloy structure is uneven and the performance is not ideal. Subsequent heat treatment is often required to further improve the alloy performance. The preparation process is complicated and cumbersome and the economy is not high. In addition, the hardness of most existing high entropy shape memory alloys is around 400HV, which is a low value and poor in practicality. Summary of the invention

[0003] The main purpose of the present invention is to provide a new TiMnFeCoNi high entropy shape memory alloy and a preparation method thereof. A new alloying element and a preparation process are introduced, and a method for preparing an equal molar ratio TiMnFeCoNi high entropy shape memory alloy by spark plasma sintering is proposed. The prepared TiMnFeCoNi high entropy shape memory alloy has good shape memory performance and superelasticity, and also has excellent mechanical properties such as hardness and compressive strength. In addition, the preparation method of spark plasma sintering can obtain a uniform and dense alloy structure, without the need for subsequent heat treatment steps, and is highly economical.

[0004] In order to solve the above technical problems, the present invention discloses a novel TiMnFeCoNi high entropy shape memory alloy and a preparation method thereof, comprising the following steps: (1) weighing a certain weight of five pure metal powders; (2) Ball milling of five kinds of pure metal powders, selecting a ball milling speed of 400 r / min and a ball milling time of 40 h, and adding an alcohol dispersant to achieve mechanical alloying; (3) Using the spark plasma sintering method, selecting appropriate sintering parameters and holding time, sintering the high entropy alloy powder; According to one embodiment of the present invention, the five pure metal powders are Ti (99.99%), Mn (99.99%), Fe (99.99%), Co (99.99%), and Ni (99.99%), with equal molar ratios, and their weights are 1.75g ​​(20at.%), 1.95g (20at.%), 2.00g (20at.%), 2.15g (20at.%), and 2.15g (20at.%), respectively, and their particle sizes are 100-300μm.

[0005] According to one embodiment of the present invention, the ball mill jar is made of stainless steel, the grinding balls are made of stainless steel, and the ball-to-material ratio is 5:1.

[0006] According to one embodiment of the present invention, the rotation speed of the ball mill is 400 r / min, the ball milling time is 40 h, the material is poured once every 10 h, and 0.4 ml of alcohol is added as a dispersant.

[0007] According to an embodiment of the present invention, among the above sintering parameters, the sintering temperature is 750-1150° C., the heating rate is 50° C. / min, the sintering pressure is 40 MPa, the vacuum degree is 40 Pa, and the holding time is 10-30 min.

[0008] Compared with the prior art, the present application can obtain the following technical effects: Of course, any product implementing the present invention does not necessarily need to achieve all of the above technical effects at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 These are the XRD test results of the TiMnFeCoNi high entropy shape memory alloys with equal molar ratios prepared in Examples 1 to 4 of the present invention.

[0010] Figure 2 These are the hardness test results of the TiMnFeCoNi high entropy shape memory alloys with equal molar ratios prepared in Examples 1 to 4 of the present invention.

[0011] Figure 3 These are the density test results of the TiMnFeCoNi high entropy shape memory alloys with equal molar ratios prepared in Examples 1 to 4 of the present invention.

[0012] Figure 4 This is a SEM image of the equimolar ratio TiMnFeCoNi high entropy shape memory alloy prepared in Example 4 of the present invention.

[0013] Figure 5 It is a SEM picture of the TiMnFeCoNi high entropy shape memory alloy with equal molar ratio prepared in Examples 1 to 4 of the present invention. DETAILED DESCRIPTION

[0014] The following will describe the implementation methods of the present application in detail with the help of accompanying drawings and examples, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0015] Please refer to Figure 1-Figure 5 , Figure 1 These are the XRD test results of the TiMnFeCoNi high entropy shape memory alloys with equal molar ratios prepared in Examples 1 to 4 of the present invention. Figure 2 These are the hardness test results of the TiMnFeCoNi high entropy shape memory alloys with equal molar ratios prepared in Examples 1 to 4 of the present invention. Figure 3 These are the density test results of the TiMnFeCoNi high entropy shape memory alloys with equal molar ratios prepared in Examples 1 to 4 of the present invention. Figure 4 This is a SEM image of the equimolar ratio TiMnFeCoNi high entropy shape memory alloy prepared in Example 4 of the present invention. Figure 5 It is a SEM picture of the TiMnFeCoNi high entropy shape memory alloy with equal molar ratio prepared in Examples 1 to 4 of the present invention.

[0016] A novel TiMnFeCoNi high entropy shape memory alloy and a preparation method thereof, comprising the following steps: (1) weighing a certain weight of five pure metal powders; (2) ball milling the five pure metal powders, selecting a ball milling speed of 400 r / min and a ball milling time of 40 h, and adding an alcohol dispersant to achieve mechanical alloying; (3) sintering the high entropy alloy powder by using a spark plasma sintering method, selecting appropriate sintering parameters and holding time; Preferably, the five pure metal powders are Ti (99.99%), Mn (99.99%), Fe (99.99%), Co (99.99%), and Ni (99.99%), with equal molar ratios, and weights of 1.75 g (20 at.%), 1.95 g (20 at.%), 2.00 g (20 at.%), 2.15 g (20 at.%), and 2.15 g (20 at.%), respectively, and a particle size of 100-300 μm.

[0017] Preferably, the ball mill is made of stainless steel, the grinding balls are made of stainless steel, and the ball-to-material ratio is 5:1.

[0018] Preferably, the ball mill speed is 400 r / min, the ball milling time is 40 h, the material is poured every 10 h, and 0.4 ml of alcohol is added as a dispersant.

[0019] Preferably, the sintering parameters include a sintering temperature of 750-1150° C., a heating rate of 50° C. / min, a sintering pressure of 40 MPa, a vacuum degree of 40 Pa, and a holding time of 10-30 min. Example 1

[0020] A method for preparing a novel TiMnFeCoNi high entropy shape memory alloy comprises the following steps: (1) Weighing of pure metal powder Use an electronic balance to weigh five pure metal powders of Ti, Mn, Fe, Co, and Ni with a purity of 99.99%, including 1.75g ​​of Ti, 1.95g of Mn, 2.00g of Fe, 2.15g of Co, and 2.15g of Ni, with a particle size of 100-300μm.

[0021] (2) Mechanical alloying of metal powder 50g of large, medium and small grinding balls and five kinds of pure metal powders were added into the grinding pot, and 0.4ml of alcohol was added. The speed of the high-energy ball mill was 400r / min, and the ball milling time was 40h. The material was poured every 10h, and 0.4ml of alcohol was added as a dispersant.

[0022] (3) Sintering high entropy alloy powder The ball-milled high entropy alloy powder was placed in a graphite mold (φ10 mm), surrounded by graphite paper, and both ends were squeezed and fixed with graphite presses. The sintering parameters included a sintering temperature of 850°C, a heating rate of 50°C / min, a sintering pressure of 40 MPa, and a vacuum of 40 Pa. The holding time was 10 min.

[0023] (4) Subsequent surface treatment of samples After sintering and cooling, the sample was demoulded, ground with sandpaper of different particle sizes, and the surface of the sample was polished with a polishing machine.

[0024] The treated samples were subjected to XRD test, and the results were as follows: Figure 1 shown.

[0025] The hardness of the treated samples was tested using a Vickers hardness tester. The results are as follows: Figure 2 As shown, its hardness value is 390.04HV.

[0026] The density of the treated samples was tested using the drainage method. The results are as follows: Figure 3 As shown, its density is 87%. Example 2

[0027] A method for preparing a novel TiMnFeCoNi high entropy shape memory alloy comprises the following steps: (1) Weighing of pure metal powder Use an electronic balance to weigh five pure metal powders of Ti, Mn, Fe, Co, and Ni with a purity of 99.99%, including 1.75g ​​of Ti, 1.95g of Mn, 2.00g of Fe, 2.15g of Co, and 2.15g of Ni, with a particle size of 100-300μm.

[0028] (2) Mechanical alloying of metal powder 50g of large, medium and small grinding balls and five kinds of pure metal powders were added into the grinding pot, and 0.4ml of alcohol was added. The speed of the high-energy ball mill was 400r / min, and the ball milling time was 40h. The material was poured every 10h, and 0.4ml of alcohol was added as a dispersant.

[0029] (3) Sintering high entropy alloy powder The ball-milled high entropy alloy powder was placed in a graphite mold (φ10 mm), surrounded by graphite paper, and fixed at both ends with graphite presses. The sintering parameters included a sintering temperature of 950 ° C, a heating rate of 50 ° C / min, a sintering pressure of 40 MPa, and a vacuum degree of 40 Pa. The holding time was 10 min.

[0030] (4) Subsequent surface treatment of samples After sintering and cooling, the sample was demoulded, ground with sandpaper of different particle sizes, and the surface of the sample was polished with a polishing machine.

[0031] The treated samples were subjected to XRD test, and the results were as follows: Figure 1 shown.

[0032] The hardness of the treated sample was tested using a Vickers hardness tester, and the hardness value was 550.12HV.

[0033] The density of the treated samples was tested using the drainage method, and the density was 94.5%. Example 3

[0034] A method for preparing a novel TiMnFeCoNi high entropy shape memory alloy comprises the following steps: (1) Weighing of pure metal powder Use an electronic balance to weigh five pure metal powders of Ti, Mn, Fe, Co, and Ni with a purity of 99.99%, including 1.75g ​​of Ti, 1.95g of Mn, 2.00g of Fe, 2.15g of Co, and 2.15g of Ni, with a particle size of 100-300μm.

[0035] (2) Mechanical alloying of metal powder 50g of large, medium and small grinding balls and five kinds of pure metal powders were added into the grinding pot, and 0.4ml of alcohol was added. The speed of the high-energy ball mill was 400r / min, and the ball milling time was 40h. The material was poured every 10h, and 0.4ml of alcohol was added as a dispersant.

[0036] (3) Sintering high entropy alloy powder The ball-milled high entropy alloy powder was placed in a graphite mold (φ10 mm), surrounded by graphite paper, and both ends were squeezed and fixed with graphite presses. The sintering parameters included a sintering temperature of 1050°C, a heating rate of 50°C / min, a sintering pressure of 40 MPa, and a vacuum of 40 Pa. The holding time was 10 min.

[0037] (4) Subsequent surface treatment of samples After sintering and cooling, the sample was demoulded, ground with sandpaper of different particle sizes, and the surface of the sample was polished with a polishing machine.

[0038] The treated samples were subjected to XRD test, and the results were as follows: Figure 1 shown.

[0039] The hardness of the treated samples was tested using a Vickers hardness tester. The results are as follows: Figure 2 As shown, its hardness value is 568.90HV.

[0040] The density of the treated samples was tested using the drainage method. The results are as follows: Figure 3 As shown, its density is 90.4%. Example 4

[0041] A method for preparing a novel TiMnFeCoNi high entropy shape memory alloy comprises the following steps: (1) Weighing of pure metal powder Use an electronic balance to weigh five pure metal powders of Ti, Mn, Fe, Co, and Ni with a purity of 99.99%, including 1.75g ​​of Ti, 1.95g of Mn, 2.00g of Fe, 2.15g of Co, and 2.15g of Ni, with a particle size of 100-300μm.

[0042] (2) Mechanical alloying of metal powder 50g of large, medium and small grinding balls and five kinds of pure metal powders were added into the grinding pot, and 0.4ml of alcohol was added. The speed of the high-energy ball mill was 400r / min, and the ball milling time was 40h. The material was poured every 10h, and 0.4ml of alcohol was added as a dispersant.

[0043] (3) Sintering high entropy alloy powder The ball-milled high entropy alloy powder was placed in a graphite mold (φ10 mm), surrounded by graphite paper, and fixed at both ends with graphite presses. The sintering parameters included a sintering temperature of 950 ° C, a heating rate of 50 ° C / min, a sintering pressure of 40 MPa, and a vacuum degree of 40 Pa. The holding time was 30 min.

[0044] (4) Subsequent surface treatment of samples After sintering and cooling, the sample was demoulded, ground with sandpaper of different particle sizes, and the surface of the sample was polished with a polishing machine.

[0045] The hardness of the treated samples was tested using a Vickers hardness tester. The results are as follows: Figure 2 As shown, its hardness value is 638HV.

[0046] The density of the treated samples was tested using the drainage method. The results are as follows: Figure 3 As shown, its density is 97.2%.

[0047] The treated samples were subjected to compression tests using a universal testing machine, and the room temperature compression recovery rate was calculated to be 5.5%, and the superelastic recovery was 11.76%.

[0048] The above description shows and describes several preferred embodiments of the present application, but as before, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the present application through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present application, and shall be within the scope of protection of the claims attached to the present application.

Claims

1. A novel TiMnFeCoNi high entropy shape memory alloy and a preparation method thereof, characterized in that: The steps include: (1) Weigh a certain weight of five kinds of pure metal powders; (2) Ball milling of five pure metal powders was performed at a ball milling speed of 400 r / min and a ball milling time of 40 h, and alcohol dispersant was added to achieve mechanical alloying; (3) Using the spark plasma sintering method, select appropriate sintering parameters and holding time to sinter the high entropy alloy powder.

2. The novel TiMnFeCoNi high entropy shape memory alloy and its preparation method according to claim 1, characterized in that: The five pure metal powders are Ti (99.99%), Mn (99.99%), Fe (99.99%), Co (99.99%), and Ni (99.99%), with equal molar ratios, and weights of 1.75g ​​(20at.%), 1.95g (20at.%), 2.00g (20at.%), 2.15g (20at.%), and 2.15g (20at.%), respectively, and particle sizes of 100-300μm.

3. The method for preparing the novel TiMnFeCoNi high entropy shape memory alloy according to claim 1, characterized in that: The ball mill is made of stainless steel, the grinding balls are made of stainless steel, and the ball-to-material ratio is 5:

1.

4. The novel TiMnFeCoNi high entropy shape memory alloy and its preparation method according to claim 1, characterized in that: The ball mill speed is 400r / min, the ball milling time is 40h, the material is poured out every 10h, and 0.4ml of alcohol is added as a dispersant.

5. The novel TiMnFeCoNi high entropy shape memory alloy and its preparation method according to claim 1, characterized in that: The sintering parameters include a sintering temperature of 750-1150° C., a heating rate of 50° C. / min, a sintering pressure of 40 MPa, and a vacuum degree of 40 Pa. The heat preservation time is 10-30 min.

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