阅读说明：本技术 一种FeCoNiSnx中熵合金及其制备方法 (FeCoNiSnxMedium-entropy alloy and preparation method thereof ) 是由 王海丰 张建宝 林怡彤 张帆 崔德旭 贺一轩 于 2021-05-27 设计创作，主要内容包括：本发明公开了一种FeCoNiSn-x中熵合金及其制备方法,其组成元素Fe、Co、Ni、Sn含量按照原子比计为1：1：1：x,当x＝0.2,0.4,0.6,0.8时为亚共晶中熵体系,x＝0.9和1时为共晶中熵体系,当x＝1.1时为过共晶中熵体系；亚共晶成分初生相为FCC相,过共晶成分初生相为Laves相,共晶合金微观组织由BCC相和Laves相组成。本发明的多主元合金体系中不含有Al、Ti、Zr等与石英试管钝化反应的元素,Fe、Co、Ni、Sn元素可以实现熔融玻璃过冷快速凝固,研究中熵合金的非平衡凝固行为。此外,本发明中随着Sn含量的增加,相变产生的双硬质BCC相和Laves相显著提高了合金的硬度和强度。(The invention discloses FeCoNiSn x The content of the constituent elements Fe, Co, Ni and Sn is 1: 1: 1: x is a hypoeutectic medium entropy system when x is 0.2, 0.4, 0.6 and 0.8, is a eutectic medium entropy system when x is 0.9 and 1, and is a hypereutectic medium entropy system when x is 1.1; the hypoeutectic composition primary phase is an FCC phase, the hypereutectic composition primary phase is a Laves phase, and the eutectic alloy microstructure consists of a BCC phase and a Laves phase. The multi-principal element alloy system does not contain elements such as Al, Ti, Zr and the like which are in passivation reaction with a quartz test tube, and Fe, Co, Ni and Sn elements can realize supercooling rapid solidification of molten glass and research the non-equilibrium solidification behavior of the entropy alloy. In addition, the hardness and the strength of the alloy are obviously improved by the double hard BCC phase and the Laves phase generated by phase transformation along with the increase of the Sn content.)

1. FeCoNiSn_xThe medium-entropy alloy is characterized in that: fe. The atomic ratio of Co, Ni and Sn is 1: x, and x is 0.2-1.1.

2. FeCoNiSn as claimed in claim 1_xThe medium-entropy alloy is characterized in that:

when x is less than 0.9, the alloy system is a hypoeutectic medium entropy system; the primary phase of the components is FCC phase.

3. FeCoNiSn as claimed in claim 1_xThe medium-entropy alloy is characterized in that:

when x is more than or equal to 0.9 and less than or equal to 1, the alloy system is an eutectic entropy system; the alloy structure of the alloy consists of BCC and Laves phases; the eutectic alloy structure is eutectic seaweed crystal structure, and the spacing between regular eutectic layer sheets is less than 600 nm.

4. FeCoNiSn as claimed in claim 1_xThe medium-entropy alloy is characterized in that:

when x is greater than 1, the alloy system is a hypereutectic medium entropy system; the primary phase of the composition is a Laves phase.

5. FeCoNiSn as claimed in claim 1_xThe medium-entropy alloy is characterized in that:

the FeCoNiSn_xThe enthalpy of mixing of Sn element and Fe, Co and Ni elements in the medium entropy alloy is respectively as follows: 11kJ/mol, 0kJ/mol and-4 kJ/mol.

6. FeCoNiSn as claimed in any of claims 1 to 5_xThe preparation method of the medium entropy alloy is characterized by comprising the following steps:

1) ingredients

Weighing clean pure metals Fe, Co, Ni and Sn as required;

2) preparation for smelting

Placing Sn at the bottom of a crucible of a smelting furnace, covering the Sn with Fe, Co and Ni, and removing oxygen in a furnace cavity;

3) melting

Smelting the alloy raw material in the smelting furnace, and cooling to obtain FeCoNiSn_xAnd (3) medium-entropy alloy.

7. FeCoNiSn according to claim 6_xThe preparation method of the medium entropy alloy is characterized in that the step 1) specifically comprises the following steps:

1.1) polishing and removing surface oxide skin of Fe, Co, Ni and Sn, and cleaning by ultrasonic waves;

the purity of the raw materials of the metal Fe, Co, Ni and Sn is more than or equal to 99.95 wt.%;

1.2) weighing pure metals Fe, Co, Ni and Sn according to the atomic ratio of 1: x, wherein x is 0.2-1.1.

8. FeCoNiSn according to claim 7_xThe preparation method of the medium entropy alloy is characterized in that the step 2) specifically comprises the following steps:

placing Sn at the bottom of a crucible of a smelting furnace, covering the Sn by Fe, Co and Ni, vacuumizing by a mechanical pump and a molecular pump in sequence, and filling protective gas until oxygen in the furnace cavity is removed.

9. FeCoNiSn according to any of claims 6 to 8_xThe preparation method of the medium entropy alloy is characterized in that the step 3) is specifically as follows:

3.1) melting the alloy raw materials in the smelting furnace into alloy liquid by an electric arc melting method, and cooling to obtain an alloy ingot;

the cooling mode adopts natural cooling in a copper mold furnace;

3.2) carrying out homogenization treatment on the alloy ingot obtained in the step 3.1) through turnover melting to obtain FeCoNiSn_xAnd (3) medium-entropy alloy.

Technical Field

The invention belongs to the technical field of alloy materials, and particularly relates to FeCoNiSn_xA medium entropy alloy and a preparation method thereof.

Background

The traditional alloy is mainly composed of one element, and the development of the multi-principal-element alloy subverts the traditional design and preparation concept of one or two-principal-element structural material alloy, and is formed by the interaction and fusion of a plurality of principal elements (the content of each element is between 5 at.% and 35 at.%). Initial research on multi-principal-element alloys has focused on the preparation of single-phase alloys with excellent mechanical properties, and in particular, on an area in which the effects of alloying elements are very active. Although the element proportion of most multi-principal element alloys is equal or close, the performance of the multi-principal element alloys is not optimal under the proportion, no effective theoretical support for the multi-principal element alloy composition design of a scientific system exists at present, and scientific problems such as tissue formation and interaction among elements in the solidification process of the multi-principal element alloys are not well understood.

Most of the existing multi-principal element alloy systems are tried by a frying method, and the elements on the periodic table are numerous, so that a large number of combination possibilities cannot be tried on all possible alloy systems one by one. Therefore, how to design a multi-principal-element alloy with excellent performance becomes one of the problems that researchers want to solve urgently.

Researches find that the development of multi-principal-element eutectic alloy can effectively solve the problem that single-phase multi-principal-element alloy cannot have the restriction of two-phase comprehensive performance and break through the defect that the strength and the plasticity of a metal material cannot be obtained at the same time, but at present, most alloy casting processes in industrial production are non-equilibrium solidification processes, and the existing eutectic medium-entropy and high-entropy alloy systems cannot realize the supercooling rapid solidification of molten glass, so that the research on the non-equilibrium solidification process and the microstructure of the medium-entropy and high-entropy alloy systems is limited.

In view of the above, the invention provides an alloy system capable of realizing supercooling and rapid solidification of molten glass, and lays a foundation for researching the non-equilibrium solidification structure of the entropy alloy.

Disclosure of Invention

The invention aims to design FeCoNiSn containing eutectic structures_xMedium entropy alloy system, x is 0.2-1.1, by increasing the content of a metal element Sn, the structure of the medium-entropy alloy is changed from hypoeutectic to eutectic and hypereutectic, and meanwhile, the glass cladding supercooling rapid solidification can be realized.

In order to achieve the purpose, the technical scheme of the invention is as follows:

FeCoNiSn_xThe medium-entropy alloy is characterized in that: fe. The atomic ratio of Co, Ni and Sn is 1: x, and x is 0.2-1.1.

Further, when x is less than 0.9, the alloy system is a hypoeutectic medium entropy system; the primary phase of the components is FCC phase.

Further, when x is more than or equal to 0.9 and less than or equal to 1, the alloy system is a eutectic entropy system; the alloy structure of the alloy consists of BCC and Laves phases; the eutectic alloy structure is eutectic seaweed crystal structure, and the spacing between regular eutectic layer sheets is less than 600 nm.

Further, when x is greater than 1, the alloy system is a hypereutectic medium entropy system; the primary phase of the composition is a Laves phase.

Further, the FeCoNiSn_xThe enthalpy of mixing of Sn element and Fe, Co and Ni elements in the medium entropy alloy is respectively as follows: 11kJ/mol, 0kJ/mol and-4 kJ/mol.

The FeCoNiSn_xThe preparation method of the medium entropy alloy is characterized by comprising the following steps:

1) ingredients

Weighing clean pure metals Fe, Co, Ni and Sn as required;

2) preparation for smelting

Placing Sn at the bottom of a crucible of a smelting furnace, covering the Sn with Fe, Co and Ni, and removing oxygen in a furnace cavity;

3) melting

Smelting the alloy raw material in the smelting furnace, and cooling to obtain FeCoNiSn_xAnd (3) medium-entropy alloy.

Further, the step 1) is specifically as follows:

1.1) polishing and removing surface oxide skin of Fe, Co, Ni and Sn, and cleaning by ultrasonic waves; the purity of the raw materials of the metal Fe, Co, Ni and Sn is more than or equal to 99.95 wt.%;

1.2) weighing pure metals Fe, Co, Ni and Sn according to the atomic ratio of 1: x, wherein x is 0.2-1.1.

Further, the step 2) is specifically as follows:

placing Sn at the bottom of a crucible of a smelting furnace, covering the Sn by Fe, Co and Ni, vacuumizing the crucible by a mechanical pump and a molecular pump in sequence, and filling protective gas until oxygen in the furnace cavity is removed;

further, the step 3) is specifically as follows:

3.1) melting the alloy raw materials in the smelting furnace into alloy liquid by an electric arc melting method, and cooling to obtain an alloy ingot; the cooling mode adopts natural cooling in a copper mold furnace; induction melting can also be adopted, but the electric arc melting is more convenient;

3.2) homogenizing the alloy ingot obtained in the step 3.1) by overturning smelting to obtain FeCoNiSn_xAnd (3) medium-entropy alloy.

The invention has the beneficial effects that:

1. the invention selects alloy elements Fe, Co, Ni and Sn which do not react with a quartz test tube, does not contain elements such as Al, Ti, Zr and the like which react with the quartz test tube, and designs FeCoNiSn_xThe preparation method of the medium-entropy alloy system is simple and efficient, and the hardness and strength of the alloy can be obviously improved by increasing the BCC phase and the Laves phase in the alloy system along with the increase of the Sn content, so that FeCoNiSn with completely eutectic alloy components is achieved_xThe eutectic entropy alloy system has excellent strength and good fluidity, effectively improves the strength and hardness of the alloy, can realize the glass cladding supercooling rapid solidification of the eutectic entropy alloy (the supercooling degree of a preliminary pre-experiment can reach more than two hundred degrees, as shown in figure 10), and simultaneously expands the research system of the eutectic entropy alloy.

2. FeCoNiSn designed by the invention_xAccording to the medium-entropy alloy, the structural transformation from hypoeutectic to complete eutectic and then to hypereutectic structures exists in the alloy structure according to the different Sn contents, and the reference guiding effect is provided for understanding the microstructure and phase transformation of the medium-entropy alloy and designing the multi-principal-element eutectic alloy with excellent strong plasticity.

Drawings

FIG. 1 shows an embodiment of the present inventionAs-cast FeCoNiSn prepared in examples 1 to 6_xXRD pattern of the alloy.

FIG. 2 shows FeCoNiSn in example 1 of the present invention_0.2SEM schematic diagram of the microstructure, a is the microstructure under low power (1000X), b is the microstructure image under high power (10000X);

FIG. 3 is FeCoNiSn of example 2 of the present invention_0.4SEM schematic diagram of the microstructure, a is the microstructure under low power (1000X), b is the microstructure image under high power (10000X);

FIG. 4 shows FeCoNiSn in example 3 of the present invention_0.6SEM schematic diagram of the microstructure, a is the microstructure under low power (1000X), b is the microstructure image under high power (10000X);

FIG. 5 shows FeCoNiSn in example 4 of the present invention_0.8SEM schematic diagram of the microstructure, a is the microstructure under low power (1000X), b is the microstructure image under high power (10000X);

FIG. 6 shows FeCoNiSn in example 5 of the present invention_1.0SEM schematic diagram of the microstructure, a is the microstructure under low power (1000X), b is the microstructure image under high power (10000X);

FIG. 7 shows FeCoNiSn in example 6 of the present invention_1.1SEM schematic diagram of the microstructure, a is the microstructure under low power (1000X), b is the microstructure image under high power (10000X);

FIG. 8 shows FeCoNiSn in example 7 of the present invention_0.9SEM schematic diagram of the microstructure, a is the microstructure under low power (1000X), b is the microstructure image under high power (10000X);

FIG. 9 shows the hardness change of as-cast FeCoNiSn alloys prepared in examples 1 to 6 of the present invention;

FIG. 10 is a graph of the large supercooling fast freezing temperature of the alloy specimen of example 5 of the present invention.

Detailed Description

The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings, and it should be noted that the embodiments are provided for the purpose of illustrating the present invention, and the scope of the present invention is not limited thereto. All other embodiments obtained by persons skilled in the art without any inventive step are within the scope of the present invention based on the specific embodiments of the present invention, and the methods not specifically described in the following specific embodiments are generally performed according to the conditions suggested by the manufacturers or according to the conventional conditions.

The embodiment of the invention comprises two parts:

the first part is to prepare FeCoNiSn containing eutectic structures_xThe medium entropy alloy system is specifically carried out according to the following steps:

step 1.1 is according to FeCoNiSn_xCalculating the atomic percent of the alloy components to obtain the corresponding mass percent of each metal element, and weighing the metal elements as raw materials, wherein the purity of each metal element is more than 99.95 wt.%.

Step 1.2, putting the raw materials into a water-cooled copper mold crucible of a vacuum smelting furnace, putting the low-melting-point element Sn at the bottom of the crucible of the smelting furnace, covering the low-melting-point element Sn with Fe, Co and Ni elements, and vacuumizing the furnace chamber to 1 multiplied by 10 by using a mechanical pump and a molecular pump in sequence^{- 3}Pa, then filling Ar gas as protective gas, and repeating the vacuumizing process for 2 times to ensure that oxygen in the furnace cavity is completely removed.

Step 1.3, firstly, a titanium ingot which is placed in advance is used for arc striking and smelting for 3-5 minutes to absorb trace oxygen which may be remained in the furnace chamber, alloy smelting is started after all parts are observed to be normal, and alloy raw materials in the smelting furnace are preliminarily smelted into alloy liquid. And after the alloy liquid is cooled, overturning and smelting for the second time by using a manipulator. And then, adding magnetic stirring in the process of repeatedly turning over the smelting for the third time and the fourth time. Finally, the fluidity and the uniformity of the alloy are checked in the fifth melting process and the sixth melting process. The smelting is carried out for three minutes each time.

And 1.4, taking out the alloy cast ingot, measuring the burning loss rate, and if the burning loss rate is less than three thousandths, meeting the conditions and analyzing a second part.

The second part is to analyze and test the micro-structure of the medium entropy alloy containing the eutectic structure, and the second part is to specifically perform the following steps:

and 2.1, firstly, cutting the alloy ingot by using the wire cut electrical discharge machining, and cutting a metallographic sample and an X-ray diffractometer (XRD) test sample into sheets with flush upper and lower surfaces.

And 2.2, inlaying the cut alloy sample, sequentially grinding with 600#, 1500#, 2500# and 4000# sandpaper, and polishing the alloy sample until the roughness of the surface to be measured is reduced to below 1.5 mu m.

Step 2.3 the phase composition of the alloy was analysed by XRD. The parameters are 40kV, the scanning angle is 20-120 degrees, and the scanning time is 25 min.

Step 2.4 use aqua regia (3HCl +1 HNO)₃) The alloy sample was corroded and microstructure observation was performed with an Olympus metallographic microscope and a Scanning Electron Microscope (SEM), respectively.

And 2.5, placing the alloy sample on a sample table of a hardness tester, debugging software and preparing a hardness experiment test, wherein the model of a compression experiment machine is an MH-5L hardness tester produced by Hengyi corporation in Shanghai, the pressure is 500gf and the load-holding time is 5s during the experiment test.

Example 1:

FeCoNiSn containing eutectic structure_0.2The medium entropy alloy system has an atomic ratio of Fe to Co to Ni to Sn of 1 to 0.2, and the specific preparation method comprises the following steps:

polishing the pure metal surface oxide layer by using sand paper, putting the pure metal surface oxide layer into an ultrasonic cleaner for cleaning by using alcohol, and calculating FeCoNiSn according to the atomic ratio_0.2And weighing the corresponding mass of Fe, Co, Ni and Sn with the purity of more than 99.95 wt.% by using a balance.

Putting the raw materials into a water-cooled copper mold crucible of a vacuum melting furnace, placing a low-melting-point Sn alloy at the bottom of the crucible during placement, then placing a titanium ingot, and vacuumizing the interior of the furnace chamber to 1 multiplied by 10 by using a mechanical pump and a molecular pump in sequence^-3Pa, and filling protective gas Ar gas, wherein the vacuumizing process needs to be repeated for 2 times to ensure that oxygen in the furnace cavity is completely removed.

Firstly, a titanium ingot placed in advance is used for arc striking and smelting for 3-5 minutes to absorb trace oxygen possibly remaining in a furnace chamber, and then the alloy raw materials are fully melted by arc smelting to obtain an alloy ingot preliminarily.

And turning over the cooled alloy ingot and smelting again, and adding magnetic stirring in the third and fourth repeated turning-over smelting processes. The alloy turnover smelting process needs to be repeated at least five times, and each time is not less than 3 minutes.

And taking out the master alloy to determine the burn-out rate, cutting the alloy ingot casting by using spark lines after the conditions are met, and cutting the metallographic sample and the XRD test sample into sheets with flush upper and lower surfaces.

Inlaying the cut alloy sample by using a sample inlaying machine, grinding by using 600#, 1500#, 2500# and 4000# sandpaper in sequence, and polishing the sample until the roughness of the surface to be measured is reduced to below 1.5 mu m.

Firstly, the medium entropy alloy prepared in example 1 is analyzed and tested by X-ray diffraction, parameters are 40kV, a scanning angle is 20-120 degrees, scanning time is 25min, and the result is shown in figure 1. FeCoNiSn can be known through comparison analysis of analysis software Jade 6.0 comparison standard PDF card_0.2Mainly composed of FCC + Laves phase.

The alloy sample of example 1 was corroded with aqua regia, and then the microstructure thereof was observed and analyzed by a metallographic microscope and an SEM, respectively. Fig. 2a shows the microstructure under a low power (1000 ×) and fig. 2b shows the microstructure under a high power (10000 ×). From the texture map, the texture is composed of black FCC primary phase regions and white lamellar eutectic regions, the white lamellae are Laves.

The alloy sample of example 1 was placed on a sample stage of a hardness tester, software was debugged and hardness test was conducted using an MH-5L hardness tester manufactured by Hengyi corporation of Shanghai under a pressure of 500gf for the test and a retention time of 5s, and the test result is shown in FIG. 9, in which FeCoNiSn_0.2The average hardness of the alloy was 214.67 HV.

Example 2:

FeCoNiSn containing eutectic structure_0.4The medium entropy alloy system has an atomic ratio of Fe to Co to Ni to Sn of 1 to 0.4, and the specific preparation method comprises the following steps:

polishing the oxide layer on the surface of the pure metal by using abrasive paper, and putting the pure metal into an ultrasonic cleaning machineCleaning with alcohol, and calculating FeCoNiSn according to the atomic ratio_0.4And weighing the corresponding mass of Fe, Co, Ni and Sn with the purity of more than 99.95 wt.% by using a balance.

Putting the raw materials into a water-cooled copper mold crucible of a vacuum melting furnace, placing a low-melting-point Sn alloy at the bottom of the crucible during placement, then placing a titanium ingot, and vacuumizing the interior of the furnace chamber to 1 multiplied by 10 by using a mechanical pump and a molecular pump in sequence^-3Pa, and filling protective gas Ar gas, wherein the vacuumizing process needs to be repeated for 2 times to ensure that oxygen in the furnace cavity is completely removed.

Firstly, a titanium ingot placed in advance is used for arc striking and smelting for 3-5 minutes to absorb trace oxygen possibly remaining in a furnace chamber, and then the alloy raw materials are fully melted by arc smelting to obtain an alloy ingot preliminarily.

And turning over the cooled alloy ingot and smelting again, and adding magnetic stirring in the third and fourth repeated turning-over smelting processes. The alloy turnover smelting process needs to be repeated at least five times, and each time is not less than 3 minutes.

And taking out the master alloy to determine the burn-out rate, cutting the alloy ingot casting by using spark lines after the conditions are met, and cutting the metallographic sample and the XRD test sample into sheets with flush upper and lower surfaces.

Inlaying the cut alloy sample by using a sample inlaying machine, grinding by using 600#, 1500#, 2500# and 4000# sandpaper in sequence, and polishing the sample until the roughness of the surface to be measured is reduced to below 1.5 mu m.

Firstly, the medium entropy alloy prepared in example 2 is analyzed and tested by X-ray diffraction, parameters are 40kV, a scanning angle is 20-120 degrees, scanning time is 25min, and the result is shown in figure 1. Compared with FeCoNiSn, the comparison result is known through comparison analysis of Jade 6.0 comparison standard PDF card of analysis software_0.2Mainly composed of FCC + Laves phase, FeCoNiSn_0.4The BCC phase peak appears.

The alloy sample of example 2 was corroded with aqua regia, and then the microstructure thereof was observed and analyzed by a metallographic microscope and SEM, respectively. FIG. 3a shows the microstructure under a low power lens (1000X), and FIG. 3b shows the microstructure under a high power lens (10000X). From the tissue map, FeCoNiSn can be seen_0.4The structure is similar and is composed of black FCC primary phase region and white lamellar eutectic region, but compared with FeCoNiSn_0.2The primary phase fraction of the alloy is gradually reduced, and the eutectic area fraction is gradually increased.

The alloy sample of example 2 was placed on a sample stage of a hardness tester, software was debugged and hardness test was carried out using an MH-5L hardness tester manufactured by Hengyi corporation of Shanghai under a pressure of 500gf and a retention time of 5s, and the test result is shown in FIG. 9, in which FeCoNiSn_0.4The average hardness of the alloy was 310.22 HV.

Example 3:

FeCoNiSn containing eutectic structure_0.6The medium entropy alloy system has the atomic ratio of Fe to Co to Ni to Sn of 1 to 0.6, and the specific preparation method comprises the following steps:

polishing the pure metal surface oxide layer by using sand paper, putting the pure metal surface oxide layer into an ultrasonic cleaner for cleaning by using alcohol, and calculating FeCoNiSn according to the atomic ratio_0.6And weighing the corresponding mass of Fe, Co, Ni and Sn with the purity of more than 99.95 wt.% by using a balance.

Putting the raw materials into a water-cooled copper mold crucible of a vacuum melting furnace, placing a low-melting-point Sn alloy at the bottom of the crucible during placement, then placing a titanium ingot, and vacuumizing the interior of the furnace chamber to 1 multiplied by 10 by using a mechanical pump and a molecular pump in sequence^-3Pa, and filling protective gas Ar gas, wherein the vacuumizing process needs to be repeated for 2 times to ensure that oxygen in the furnace cavity is completely removed.

Firstly, a titanium ingot placed in advance is used for arc striking and smelting for 3-5 minutes to absorb trace oxygen possibly remaining in a furnace chamber, and then the alloy raw materials are fully melted by arc smelting to obtain an alloy ingot preliminarily.

And turning over the cooled alloy ingot and smelting again, and adding magnetic stirring in the third and fourth repeated turning-over smelting processes. The alloy turnover smelting process needs to be repeated at least five times, and each time is not less than 3 minutes.

And taking out the master alloy to determine the burn-out rate, cutting the alloy ingot casting by using spark lines after the conditions are met, and cutting the metallographic sample and the XRD test sample into sheets with flush upper and lower surfaces.

Inlaying the cut alloy sample by using a sample inlaying machine, grinding by using 600#, 1500#, 2500# and 4000# sandpaper in sequence, and polishing the sample until the roughness of the surface to be measured is reduced to below 1.5 mu m.

Firstly, the medium entropy alloy prepared in example 3 is analyzed and tested by X-ray diffraction, parameters are 40kV, a scanning angle is 20-120 degrees, scanning time is 25min, and the result is shown in figure 1. Through analysis software Jade 6.0 comparison standard PDF card comparison analysis, the intensity of the phase peak of the primary phase FCC is greatly weakened, and FeCoNiSn_0.6Mainly composed of BCC + Laves phase.

The alloy sample of example 3 was corroded with aqua regia, and then the microstructure thereof was observed and analyzed by a metallographic microscope and an SEM, respectively. Fig. 4a shows the microstructure under a low power (1000X) and fig. 4b shows the microstructure under a high power (10000X). The alloy structure is mainly a eutectic lamellar area in the structure diagram, and the fraction of a primary phase is greatly reduced consistent with the XRD result.

The alloy sample of example 3 was placed on a sample stage of a hardness tester, software was debugged and hardness test was carried out using an MH-5L hardness tester manufactured by Hengyi corporation of Shanghai under a pressure of 500gf and a retention time of 5s, and the test result is shown in FIG. 9, in which FeCoNiSn_0.6The average hardness of the alloy was 401.65 HV.

Example 4:

FeCoNiSn containing eutectic structure_0.8The medium entropy alloy system has an atomic ratio of Fe to Co to Ni to Sn of 1 to 0.8, and the specific preparation method comprises the following steps:

polishing the pure metal surface oxide layer by using sand paper, putting the pure metal surface oxide layer into an ultrasonic cleaner for cleaning by using alcohol, and calculating FeCoNiSn according to the atomic ratio_0.8And weighing the corresponding mass of Fe, Co, Ni and Sn with the purity of more than 99.95 wt.% by using a balance.

Water-cooled copper mold crucible for putting raw materials into vacuum smelting furnaceIn the crucible, the low melting point Sn alloy is placed at the bottom of the crucible when placed, then a titanium ingot is placed, and the inside of the furnace chamber is vacuumized to 1 multiplied by 10 by using a mechanical pump and a molecular pump in sequence^-3Pa, and filling protective gas Ar gas, wherein the vacuumizing process needs to be repeated for 2 times to ensure that oxygen in the furnace cavity is completely removed.

Firstly, a titanium ingot placed in advance is used for arc striking and smelting for 3-5 minutes to absorb trace oxygen possibly remaining in a furnace chamber, and then the alloy raw materials are fully melted by arc smelting to obtain an alloy ingot preliminarily.

And turning over the cooled alloy ingot and smelting again, and adding magnetic stirring in the third and fourth repeated turning-over smelting processes. The alloy turnover smelting process needs to be repeated at least five times, and each time is not less than 3 minutes.

And taking out the master alloy to determine the burn-out rate, cutting the alloy ingot casting by using spark lines after the conditions are met, and cutting the metallographic sample and the XRD test sample into sheets with flush upper and lower surfaces.

Inlaying the cut alloy sample by using a sample inlaying machine, grinding by using 600#, 1500#, 2500# and 4000# sandpaper in sequence, and polishing the sample until the roughness of the surface to be measured is reduced to below 1.5 mu m.

Firstly, the medium entropy alloy prepared in example 4 is analyzed and tested by X-ray diffraction, parameters are 40kV, a scanning angle is 20-120 degrees, scanning time is 25min, and the result is shown in figure 1. Through analysis software Jade 6.0 comparison standard PDF card comparison analysis, the phase peak of primary phase FCC, FeCoNiSn, can not be seen in XRD pattern_0.8Mainly composed of BCC + Laves phase.

The alloy sample of example 4 was corroded with aqua regia, and then the microstructure thereof was observed and analyzed by a metallographic microscope and an SEM, respectively. Fig. 5a shows the microstructure under a low power (1000 ×) and fig. 5b shows the microstructure under a high power (10000 ×). From the tissue map, the gene is shown to be in contact with FeCoNiSn_0.8The structure is similar, the alloy structure is mainly a eutectic lamellar area and a small amount of primary phase appears.

Placing the alloy sample of example 4 on a sample table of a hardness tester, debugging software and preparing a hardness testerThe test was carried out using a durometer model MH-5L manufactured by Heng-Inc. of Shanghai under a pressure of 500gf and a holding time of 5s, and the test results are shown in FIG. 9, in which FeCoNiSn_0.8The average hardness of the alloy was 706.75 HV.

Example 5:

a FeCoNiSn intermediate entropy alloy system containing a complete eutectic structure has an atomic ratio of Fe to Co to Ni to Sn of 1 to 1, and the specific preparation method comprises the following steps:

and (2) polishing an oxide layer on the surface of the pure metal by using sand paper, putting the pure metal into an ultrasonic cleaner, cleaning the pure metal by using alcohol, calculating the mass ratio of the FeCoNiSn alloy according to the atomic ratio, and then weighing corresponding masses of Fe, Co, Ni and Sn elements with the purity of more than 99.95 wt.% by using a balance.

Putting the raw materials into a water-cooled copper mold crucible of a vacuum melting furnace, placing a low-melting-point Sn alloy at the bottom of the crucible during placement, then placing a titanium ingot, and vacuumizing the interior of the furnace chamber to 1 multiplied by 10 by using a mechanical pump and a molecular pump in sequence^-3Pa, and filling protective gas Ar gas, wherein the vacuumizing process needs to be repeated for 2 times to ensure that oxygen in the furnace cavity is completely removed.

Firstly, a titanium ingot placed in advance is used for arc striking and smelting for 3-5 minutes to absorb trace oxygen possibly remaining in a furnace chamber, and then the alloy raw materials are fully melted by arc smelting to obtain an alloy ingot preliminarily.

And turning over the cooled alloy ingot and smelting again, and adding magnetic stirring in the third and fourth repeated turning-over smelting processes. The alloy turnover smelting process needs to be repeated at least five times, and each time is not less than 3 minutes.

And taking out the master alloy to determine the burn-out rate, cutting the alloy ingot casting by using spark lines after the conditions are met, and cutting the metallographic sample and the XRD test sample into sheets with flush upper and lower surfaces.

Inlaying the cut alloy sample by using a sample inlaying machine, grinding by using 600#, 1500#, 2500# and 4000# sandpaper in sequence, and polishing the sample until the roughness of the surface to be measured is reduced to below 1.5 mu m.

Firstly, the entropy combination in the eutectic prepared in example 5 is analyzed and tested by X-ray diffraction, parameters are 40kV, the scanning angle is 20-120 degrees, the scanning time is 25min, and the result is shown in figure 1. As can be seen by comparison analysis of analysis software Jade 6.0 and standard PDF card, the phase peak of primary phase FCC can not be seen in the XRD map, and the FeCoNiSn alloy structure mainly comprises BCC + Laves phase.

The alloy sample of example 5 was corroded with aqua regia, and then the microstructure thereof was observed and analyzed by a metallographic microscope and an SEM, respectively. Fig. 6a shows the microstructure under a low power (1000 ×) and fig. 6b shows the microstructure under a high power (10000 ×). The structural diagram shows that the FeCoNiSn alloy structure is a complete eutectic lamellar region, namely a eutectic seaweed crystal structure, and the regular eutectic lamellar spacing is below 600 nm. The enthalpy of mixing of Sn element and Fe, Co and Ni elements in the FeCoNiSn medium entropy alloy is respectively as follows: 11kJ/mol, 0kJ/mol and-4 kJ/mol.

The alloy sample of example 5 was placed on a sample stage of a hardness tester, software was debugged, and a hardness test was prepared using an MH-5L durometer manufactured by shanghai hengyi corporation, the pressure was 500gf, the retention time was 5s, and the test result is shown in fig. 9, in which the average value of the hardness of the FeCoNiSn alloy was 710.93 HV.

Example 6:

FeCoNiSn containing eutectic structure_1.1The medium entropy alloy system has an atomic ratio of Fe to Co to Ni to Sn of 1 to 1.1, and the specific preparation method comprises the following steps:

polishing the pure metal surface oxide layer by using sand paper, putting the pure metal surface oxide layer into an ultrasonic cleaner for cleaning by using alcohol, and calculating FeCoNiSn according to the atomic ratio_1.1And weighing the corresponding mass of Fe, Co, Ni and Sn with the purity of more than 99.95 wt.% by using a balance.

Putting the raw materials into a water-cooled copper mold crucible of a vacuum melting furnace, placing a low-melting-point Sn alloy at the bottom of the crucible during placement, then placing a titanium ingot, and vacuumizing the interior of the furnace chamber to 1 multiplied by 10 by using a mechanical pump and a molecular pump in sequence^-3Pa, and introducing protective gas Ar gas, and repeating the vacuum-pumping process for 2 times to ensure that oxygen in the furnace cavity is exhaustedAnd (3) cleaning.

Firstly, a titanium ingot placed in advance is used for arc striking and smelting for 3-5 minutes to absorb trace oxygen possibly remaining in a furnace chamber, and then the alloy raw materials are fully melted by arc smelting to obtain an alloy ingot preliminarily.

And turning over the cooled alloy ingot and smelting again, and adding magnetic stirring in the third and fourth repeated turning-over smelting processes. The alloy turnover smelting process needs to be repeated at least five times, and each time is not less than 3 minutes.

And taking out the master alloy to determine the burn-out rate, cutting the alloy ingot casting by using spark lines after the conditions are met, and cutting the metallographic sample and the XRD test sample into sheets with flush upper and lower surfaces.

Inlaying the cut alloy sample by using a sample inlaying machine, grinding by using 600#, 1500#, 2500# and 4000# sandpaper in sequence, and polishing the sample until the roughness of the surface to be measured is reduced to below 1.5 mu m.

Firstly, the intermediate entropy product prepared in example 6 is analyzed and tested by X-ray diffraction, parameters are 40kV, the scanning angle is 20-120 degrees, the scanning time is 25min, and the result is shown in figure 1. Through the comparison and analysis of Jade 6.0 comparison standard PDF card of analysis software, FeCoNiSn_1.1The XRD pattern peaks of (A) mainly consist of two hard BCC + Laves phase peaks.

The alloy sample of example 6 was corroded with aqua regia, and then the microstructure thereof was observed and analyzed by a metallographic microscope and an SEM, respectively. Fig. 7a shows the microstructure under a low power (1000 ×) and fig. 7b shows the microstructure under a high power (10000 ×). From the tissue diagram, FeCoNiSn is seen_1.1In the case of hypereutectic alloys, the alloy structure is composed of eutectic lamellar regions and Laves primary phases.

The alloy sample of example 6 was placed on a sample stage of a hardness tester, software was debugged and hardness test was conducted using an MH-5L hardness tester manufactured by Hengyi corporation of Shanghai under a pressure of 500gf for the test and a retention time of 5s, and the test result is shown in FIG. 9, in which FeCoNiSn_1.1The average hardness of the alloy is 766.12HV, and the plasticity is relatively poor.

Example 7

The difference from example 5 is that the atomic ratio x of Sn is 0.9. FeCoNiSn containing complete eutectic structure_0.9The specific preparation method of the alloy sample is completely the same as that of the example 5.

The alloy sample of example 7 was corroded with aqua regia, and then the microstructure thereof was observed and analyzed by a metallographic microscope and an SEM, respectively. Fig. 8a shows the microstructure under a low power (1000 ×) and fig. 8b shows the microstructure under a high power (10000 ×). From the tissue diagram, FeCoNiSn is seen_0.9The alloy structure is a fully eutectic lamellar region, consistent with the fully eutectic structure in example 5. In other words, the complete eutectic of the system has a certain composition range, and the alloy with the complete eutectic composition is not strictly limited by a specific composition point, which is a great advantage of the invention, so that the requirements on material purity and proportioning in the alloy application process are greatly reduced, and the system is very suitable for industrial production.

The above examples contain eutectic structures of FeCoNiSn_xThe medium-entropy alloy system is designed according to the atomic ratio, the atomic ratio content of alloy constituent elements Fe, Co, Ni and Sn is 1: x respectively, wherein x is 0.2-1.1; from the above experimental results, it is found that the hypoeutectic medium entropy system is obtained when x is 0.2, 0.4, 0.6, 0.8, the eutectic medium entropy system is obtained when x is 0.9, 1, and the hypereutectic medium entropy system is obtained when x is 1.1, that is, when x is 0.2, 0.4, 0.6, 0.8<0.9 hour is hypoeutectic medium entropy system, and its primary phase is FCC phase; when x is more than or equal to 0.9 and less than or equal to 1, the eutectic medium entropy system is formed, and the alloy structure of the eutectic medium entropy system consists of BCC and Laves phases; when x is>The phase 1 is a hypereutectic medium entropy system, and the primary phase of the composition is a Laves phase. With the increase of the Sn content, the structure of the medium-entropy alloy is changed from hypoeutectic to eutectic and then to hypereutectic, the BCC phase, especially the Laves phase in the alloy is increased continuously, and the hardness of the alloy is also improved continuously.

When numerical values are included in the claims of the present invention, it should be noted that numerical values between each numerical value can be selected, and since the steps and methods adopted are the same as those of the embodiments, the present invention describes preferred embodiments and effects thereof in order to prevent redundancy. Additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

Although embodiments of the present invention have been described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.