A method for synergistically improving the strength and plasticity of AlCoCrFeNi2.1 eutectic high entropy alloy

Abstract

The present invention relates to the technical field of metal materials, and in particular to a method for synergistically improving the strength and plasticity of an AlCoCrFeNi2.1 eutectic high entropy alloy, comprising the following steps: Step 1: repeatedly heating and melting Al, Co, Cr, Fe, and Ni particles in a vacuum arc melting furnace to obtain an alloy button ingot; Step 2: ultrasonically treating the prepared alloy button ingot using an ultrasonic assisted forming technology, and obtaining a eutectic high entropy alloy with enhanced ultimate tensile stress and enhanced plasticity after ultrasonic treatment; the purity of Al, Co, Cr, Fe, and Ni is higher than 99.9%; the atomic percentages of Al, Co, Cr, Fe, and Ni are 1:1:1:1:2.1. The AlCoCrFeNi2.1 eutectic high entropy alloy prepared by the preparation method of the present invention has improved strength and plasticity. The experimental results of the present invention show that ultrasonic assisted loading can simultaneously improve the strength and plasticity of the AlCoCrFeNi2.1 eutectic high entropy alloy, which provides a new idea for developing eutectic high entropy alloy materials with excellent comprehensive mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of metal materials, and in particular to a method for synergistically improving the strength and plasticity of an AlCoCrFeNi2.1 eutectic high entropy alloy. Background Art

[0002] Compared with the design concept of traditional alloys with one element as the main element, high entropy alloys are solid solution alloys formed by mixing multiple components in equimolar or nearly equimolar ratios. The high mixing entropy reduces the Gibbs free energy of the system, which is conducive to the formation of simple face-centered cubic (FCC) and body-centered cubic (BCC) solid solution structures. However, the complex interaction between multiple main elements often makes the alloy consist of multiple phases, including simple solid solution, ordered solid solution, intermetallic compounds, etc., so that the alloy presents different microstructures. Eutectic structure is a very typical one among many microstructures. AlCoCrFeNi2.1 eutectic high entropy alloy is a recently proposed non-equimolar high entropy alloy. The investigation found that AlCoCrFeNi2.1 eutectic high entropy alloy has a FCC+BCC two-phase structure, and its microstructure is a typical fine lamellar eutectic structure. The cast AlCoCrFeNi2.1 eutectic high entropy alloy has good comprehensive mechanical properties, but considering that the hard and brittle body-centered cubic phase in the alloy exists in a coarse lamellar form, the improvement of the alloy performance is limited. Although there are many methods currently used to improve the mechanical properties of eutectic high entropy alloys, each of them has its own shortcomings, such as: 1. The samples are often subjected to large deformation by supercooling and superheating treatment, and the steps are cumbersome and the operation is complicated; 2. Although high-temperature solid solution strengthening can effectively improve its mechanical properties. However, due to the complex and diverse composition of eutectic high entropy alloys, the solid solubility between different metal elements varies greatly, so the selection of solid solution temperature and time is difficult to meet the requirements of all elements. At the same time, high-temperature solid solution is also prone to cause problems such as grain boundary coarsening and phase separation, further limiting the performance improvement of the material; 3. The grain size is usually controlled by controlling the cooling rate. However, due to the complex composition of eutectic high entropy alloys, the chemical reactions and phase change behaviors between the elements are difficult to accurately predict, resulting in the grain size being difficult to control. Therefore, there is an urgent need for a treatment process that can improve the mechanical properties of eutectic high entropy alloys through simple non-thermal treatment. Summary of the invention

[0003] The object of the present invention is to provide a method for synergistically improving the strength and plasticity of AlCoCrFeNi2.1 eutectic high entropy alloy, which can solve the above-mentioned technical problems.

[0004] The present invention provides a method for synergistically improving the strength and plasticity of an AlCoCrFeNi2.1 eutectic high entropy alloy, characterized in that it comprises the following steps:

[0005] Step 1: repeatedly heating and melting Al, Co, Cr, Fe, and Ni particles in a vacuum arc melting furnace to obtain an alloy button ingot;

[0006] Step 2: The prepared alloy button ingot is subjected to ultrasonic treatment by ultrasonic assisted forming technology, and a eutectic high entropy alloy with enhanced ultimate tensile stress and enhanced plasticity can be obtained after ultrasonic treatment;

[0007] The purity of Al, Co, Cr, Fe and Ni is higher than 99.9%; the atomic percentage of Al, Co, Cr, Fe and Ni is 1:1:1:1:2.1.

[0008] Preferably, the heating and melting are repeated 5 times in step 1.

[0009] Preferably, the melting in step 1 is carried out in an argon atmosphere.

[0010] Preferably, in step 1, magnetic stirring is turned on during the melting process.

[0011] Preferably, during the repeated heating and melting process in step 1, the alloy button ingot is heated so that it completely becomes a molten state within 10 seconds.

[0012] Preferably, in step 2, the alloy button ingot is placed at the bottom of the ultrasonic device, and the energy rod that outputs ultrasound first compacts the alloy button ingot to a preset holding pressure, and then the ultrasonic experiment is started.

[0013] Preferably, the frequency of ultrasound in step 2 is 2.0×10 4 Hz~10 12 Hz, the holding pressure is 6000N, and the ultrasonic time is 10min-20min.

[0014] Beneficial effects of the present invention:

[0015] The present invention uses an arc melting method to repeatedly melt the alloy so that the raw materials are evenly mixed, and a cast AlCoCrFeNi2.1 eutectic high entropy alloy is obtained. Subsequently, an ultrasonic treatment device is used to perform ultrasonic treatment on the above-mentioned eutectic high entropy alloy for different times. The preparation process is simple, the repeatability is high, the ultrasonic treatment time is short, and the frequency is controllable, so the prepared sample microstructure and performance can be flexibly adjusted as needed. The eutectic high entropy alloy without ultrasonic treatment (original state) has two phases distributed in lamellar layers, the length of the eutectic lamellar structure is basically the same, and there are coarse dendrites of the BCC phase distributed in the non-lamellar area. With the increase of ultrasonic-assisted loading time, the coarse dendrites of the BCC phase gradually refine and disperse more evenly, the eutectic lamellar structure becomes shorter and the lamellar structure becomes wider, and such a structure makes the strength and plasticity of the AlCoCrFeNi2.1 eutectic high entropy alloy improved at the same time. This method of improving mechanical properties by ultrasonic treatment provides a new idea for optimizing the mechanical properties of eutectic high entropy alloy system materials, and has important engineering application significance.

[0016] The AlCoCrFeNi2.1 eutectic high entropy alloy prepared by the preparation method of the present invention has improved strength and plasticity. For the original AlCoCrFeNi2.1 eutectic high entropy alloy, its ultimate tensile stress can reach 915MPa and its elongation is 15.5%. The AlCoCrFeNi2.1 eutectic high entropy alloy prepared under ultrasonic loading time of 10min and 20min respectively has an ultimate tensile stress of 918MPa and 971Mpa, and its elongation is 19.6% and 25%, respectively. Compared with the original state, the plasticity is improved, especially the AlCoCrFeNi2.1 eutectic high entropy alloy after ultrasonic treatment for 20min, the strength and plasticity are improved at the same time. The experimental results of the present invention show that ultrasonic assisted loading can improve the strength and plasticity of the AlCoCrFeNi2.1 eutectic high entropy alloy at the same time, which provides a new idea for the development of eutectic high entropy alloy materials with excellent comprehensive mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for synergistically improving the strength and plasticity of an AlCoCrFeNi2.1 eutectic high entropy alloy according to the present invention;

[0019] Figure 2 A schematic diagram of an ultrasonic assisted forming device used in the present invention;

[0020] Figure 3 The morphology of the original state, sample after 10min and 20min ultrasonic treatment of AlCoCrFeNi2.1 eutectic high entropy alloy;

[0021] Figure 4 EDS spectrum composition analysis of AlCoCrFeNi2.1 eutectic high entropy alloy;

[0022] Figure 5 These are the mechanical property curves of the AlCoCrFeNi2.1 eutectic high entropy alloy samples in their original state, after 10 minutes and 20 minutes of ultrasonic treatment.

[0023] Explanation of the reference numerals: 1- bracket, 2- transducer, 3- amplitude transformer, 4- tool head, 5- base, 6- limiting block. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this description, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for synergistically improving the strength and plasticity of an AlCoCrFeNi2.1 eutectic high entropy alloy comprises the following steps:

[0029] S1. Al, Co, Cr, Fe and Ni single-substance particles with a purity higher than 99.9% are prepared in an atomic percentage of 1:1:1:1:2.1, and then melted repeatedly in a vacuum arc melting furnace for 5 times, the melting is carried out in an argon atmosphere, and magnetic stirring is turned on during the melting process to obtain AlCoCrFeNi2.1 alloy button ingots; in addition, during the repeated heating and melting, the alloy button ingots are heated so that they are completely molten within 10 seconds;

[0030] S2. The prepared AlCoCrFeNi2.1 alloy button ingot was ultrasonically treated by ultrasonic vibration loading technology. The frequency of the ultrasound was 2.0×10 4 Hz~10 12 Hz, the holding pressure is 6000N, the ultrasonic time is 20min, and the eutectic high entropy alloy with an ultimate tensile stress of 971MPa and a plasticity of 25% is obtained.

[0031] The ultrasonic processing technology adopts an ultrasonic assisted forming device (ultrasonic device), which includes a bracket 1, a transducer 2, a horn 3 and a tool head 4. The transducer 2 is connected to an ultrasonic power supply. A base 5 is provided below the position corresponding to the tool head 4. A limiting block 6 is provided on the base 5 corresponding to the side of the tool head 4. The alloy button ingot is placed between the limiting blocks 6 and transmitted to the tool head 4 through the horn 3 to make it vibrate, thereby ultrasonically treating the AlCoCrFeNi2.1 eutectic high entropy alloy. Figure 2 The ultrasonic assisted forming device shown is mainly for demonstrating the positional relationship of the placement of the alloy button ingots. The ultrasonic assisted forming device used in the present invention is an existing device, and not all of its structures are illustrated.

[0032] Example 2

[0033] The steps are mostly the same as those in Example 1, with the only difference being that the ultrasonication time is 10 min.

[0034] Experimental Results

[0035] like Figure 3-5 As shown, compared with the samples produced by arc melting and casting, ultrasonic vibration treatment can slightly improve the strength of AlCoCrFeNi2.1 eutectic high entropy alloy and significantly enhance its plasticity.

[0036] Depend on Figure 2 The schematic diagram of the ultrasonic assisted forming device can obtain the ultrasonic vibration treatment process, and the melted AlCoCrFeNi2.1 eutectic high entropy alloy sample is subjected to ultrasonic treatment for different time periods in a preset holding pressure environment.

[0037] Depend on Figure 3The backscattering morphology results show that compared with the AlCoCrFeNi2.1 eutectic high entropy alloy prepared by arc melting and casting, the coarse BCC dendrites of the eutectic high entropy alloy treated by ultrasound are significantly refined, the distribution of FCC and BCC phases is more uniform than that of the original state, and the eutectic layer structure becomes shorter and wider. Figure 4 From the EDS energy spectrum composition analysis, it can be seen that the EDS diagram shows the element distribution of AlCoCrFeNi2.1 eutectic high entropy alloy, the BCC phase is rich in NiAl; the FCC phase is rich in CoCrFe.

[0038] from Figure 5 From the stress-strain curve, compared with the AlCoCrFeNi2.1 eutectic high entropy alloy prepared by arc melting and casting, the plasticity of the AlCoCrFeNi2.1 eutectic high entropy alloy prepared under ultrasonic assisted loading time of 10min and 20min is improved. The strength and plasticity of the sample treated with ultrasonic treatment for 20min are improved at the same time. The treatment results show that ultrasonic vibration loading can improve the strength and plasticity of AlCoCrFeNi2.1 eutectic high entropy alloy at the same time.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synergistically improving the strength and plasticity of AlCoCrFeNi2.1 eutectic high entropy alloy. It is characterized in that The following steps are involved: Step 1: repeatedly heating and melting Al, Co, Cr, Fe and Ni particles in a vacuum arc melting furnace to obtain alloy button ingots, and the number of repeated heating and melting is 5 times; Step 2: The prepared alloy button ingot is ultrasonically treated by ultrasonic assisted forming technology. After ultrasonic treatment, a eutectic high entropy alloy with enhanced ultimate tensile stress and plasticity can be obtained. In step 2, the alloy button ingot is placed at the bottom of the ultrasonic device, and the energy rod that outputs ultrasound first compacts the alloy button ingot to a preset holding pressure, and then the ultrasonic experiment is started. The frequency of the ultrasound in step 2 is 2.0×10 4 Hz-10 12 Hz, holding pressure is 6000N, ultrasonic time is 10min-20min; The purity of Al, Co, Cr, Fe and Ni is higher than 99.9%; the atomic percentage of Al, Co, Cr, Fe and Ni is 1:1:1:1:2.

1.

2. The method for synergistically improving the strength and plasticity of the AlCoCrFeNi2.1 eutectic high entropy alloy according to claim 1, It is characterized in that In the step 1, the melting is carried out in an argon atmosphere.

3. The method for synergistically improving the strength and plasticity of the AlCoCrFeNi2.1 eutectic high entropy alloy according to claim 1, It is characterized in that In the step 1, magnetic stirring is turned on during the melting process.

4. The method for synergistically improving the strength and plasticity of the AlCoCrFeNi2.1 eutectic high entropy alloy according to claim 1, It is characterized in that In the repeated heating and melting process of step 1, the alloy button ingot is heated so that it completely becomes a molten state within 10 seconds.

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