HIGH-STRENGTH AND HIGH-PLASTICITY CASTING HIGH-ENTROPY ALLOY (HEA) AND PREPARATION METHOD THEREOF

Abstract

The present disclosure provides a high-strength and high-plasticity casting high-entropy alloy (HEA), having a general formula of Al.sub.aCo.sub.bCr.sub.cTi.sub.dFe.sub.eNi.sub.fCu.sub.g, where 6.0<a≤8.0, 18.0<b≤23.0, 7.5≤c<12.5, 2.0<d≤8.5, 15.5<e≤20.0, 28.0<f≤37.0, 0.2<g≤10.0, and a+b+c+d+e+f+g=100. The casting HEA can be prepared in one step and has excellent mechanical properties. The various metal raw materials are environmental-friendly and suitable for large-scale industrial production.

Claims

1. A high-strength and high-plasticity casting high-entropy alloy (HEA), having a general formula of Al.sub.aCo.sub.bCr.sub.cTi.sub.dFe.sub.eNi.sub.fCu.sub.g, wherein 6.0<a≤8.0, 18.0<b≤23.0, 7.5≤c<12.5, 2.0<d≤8.5, 15.5<e≤20.0, 28.0<f≤37.0, 0.2<g≤10.0, and a+b+c+d+e+f+g=100.

2. The high-strength and high-plasticity casting HEA according to claim 1, wherein in the general formula of the HEA, 6.9<a≤7.5, 20.2<b≤21.9, 10.1≤c<11.0, 4.6<d≤5.0, 20.2<e≤21.9, 30.3<f≤32.9, and 0.5<g≤7.5.

3. The high-strength and high-plasticity casting HEA according to claim 1, wherein the HEA has a tensile strength of 900 MPa to 1,200 MPa and an elongation of 15% to 24%.

4. A preparation method of the high-strength and high-plasticity casting HEA according to claim 1, comprising the following steps: step 1): completely cleaning bulk particles of Al, Co, Cr, Cu, Fe, Ni, and Ti elementary substances, and weighing according to a proportion; step 2): vacuumizing a vacuum smelting furnace to not more than 6.0×10.sup.−4 Pa, and introducing a protective gas; adding Ti into the vacuum smelting furnace for deoxidation, adding the rest of the elementary substances for melting, and stirring for smelting; and step 3): after the smelting is completed, pouring an alloy obtained in step 2) into a water cooling plate-shaped copper mold for casting, cooling to room temperature, and collecting a finished product.

5. The preparation method of the high-strength and high-plasticity casting HEA according to claim 4, wherein in the general formula of the HEA, 6.9<a≤7.5, 20.2<b≤21.9, 10.1<c≤11.0, 4.6<d≤5.0, 20.2<e≤21.9, 30.3<f≤32.9, and 0.5<g≤7.5.

6. The preparation method of the high-strength and high-plasticity casting HEA according to claim 4, wherein the HEA has a tensile strength of 900 MPa to 1,200 MPa and an elongation of 15% to 24%.

7. The preparation method of the high-strength and high-plasticity casting HEA according to claim 4, wherein in step 1), the elementary substances each have a purity of not less than 99.95%.

8. The preparation method of the high-strength and high-plasticity casting HEA according to claim 5, wherein in step 1), the elementary substances each have a purity of not less than 99.95%.

9. The preparation method of the high-strength and high-plasticity casting HEA according to claim 6, wherein in step 1), the elementary substances each have a purity of not less than 99.95%.

10. The preparation method of the high-strength and high-plasticity casting HEA according to claim 4, wherein in step 2), the vacuum smelting furnace is a vacuum arc smelting furnace or a vacuum induction smelting furnace.

11. The preparation method of the high-strength and high-plasticity casting HEA according to claim 5, wherein in step 2), the vacuum smelting furnace is a vacuum arc smelting furnace or a vacuum induction smelting furnace.

12. The preparation method of the high-strength and high-plasticity casting HEA according to claim 6, wherein in step 2), the vacuum smelting furnace is a vacuum arc smelting furnace or a vacuum induction smelting furnace.

13. The preparation method of the high-strength and high-plasticity casting HEA according to claim 4, wherein in step 2), the protective gas is argon or other gas that does not react with metal raw materials, having a purity of 99.999%.

14. The preparation method of the high-strength and high-plasticity casting HEA according to claim 5, wherein in step 2), the protective gas is argon or other gas that does not react with metal raw materials, having a purity of 99.999%.

15. The preparation method of the high-strength and high-plasticity casting HEA according to claim 6, wherein in step 2), the protective gas is argon or other gas that does not react with metal raw materials, having a purity of 99.999%.

16. The preparation method of the high-strength and high-plasticity casting HEA according to claim 4, wherein in step 2), the smelting is conducted by overturning type smelting 5 times with 5 min in each time.

17. The preparation method of the high-strength and high-plasticity casting HEA according to claim 5, wherein in step 2), the smelting is conducted by overturning type smelting 5 times with 5 min in each time.

18. The preparation method of the high-strength and high-plasticity casting HEA according to claim 6, wherein in step 2), the smelting is conducted by overturning type smelting 5 times with 5 min in each time.

19. The preparation method of the high-strength and high-plasticity casting HEA according to claim 4, wherein in step 3), the alloy has a thickness of not less than 8 mm.

20. The preparation method of the high-strength and high-plasticity casting HEA according to claim 4, wherein in step 3), the alloy has a uniformly-distributed dendritic structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 shows comparison photos of an Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA sample prepared in Example 1 before and after stretching;

[0026] FIG. 2 shows an engineering stress-strain curve of static stretching of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0027] FIG. 3 shows a metallographic diagram of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0028] FIG. 4 shows a secondary electron image of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0029] FIG. 5A shows a scanning electron microscope image of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0030] FIG. 5B shows an X-ray energy spectrum-based Al element area profile of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0031] FIG. 5C shows an X-ray energy spectrum-based Co element area profile of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0032] FIG. 5D shows an X-ray energy spectrum-based Cr element area profile of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0033] FIG. 5E shows an X-ray energy spectrum-based Cu element area profile of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0034] FIG. 5F shows an X-ray energy spectrum-based Ti element area profile of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0035] FIG. 5G shows an X-ray energy spectrum-based Ni element area profile of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1;

[0036] FIG. 5H shows an X-ray energy spectrum-based Fe element area profile of the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in Example 1.

[0037] FIG. 6 shows comparison photos of an Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA sample prepared in Example 2 before and after stretching;

[0038] FIG. 7 shows an engineering stress-strain curve of static stretching of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0039] FIG. 8 shows a metallographic diagram of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0040] FIG. 9 shows a secondary electron image of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0041] FIG. 10A shows a scanning electron microscope image of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0042] FIG. 10B shows an X-ray energy spectrum-based Al element area profile of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0043] FIG. 10C shows an X-ray energy spectrum-based Co element area profile of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0044] FIG. 10D shows an X-ray energy spectrum-based Cr element area profile of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0045] FIG. 10E shows an X-ray energy spectrum-based Ti element area profile of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0046] FIG. 1OF shows an X-ray energy spectrum-based Fe element area profile of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0047] FIG. 10G shows an X-ray energy spectrum-based Ni element area profile of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2;

[0048] FIG. 10H shows an X-ray energy spectrum-based Cu element area profile of the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in Example 2.

[0049] FIG. 11 shows comparison photos of an Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA sample prepared in Example 3 before and after stretching;

[0050] FIG. 12 shows an engineering stress-strain curve of static stretching of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0051] FIG. 13 shows a metallographic diagram of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0052] FIG. 14 shows a secondary electron image of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0053] FIG. 15A shows a scanning electron microscope image of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0054] FIG. 15B shows an X-ray energy spectrum-based Al element area profile of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0055] FIG. 15C shows an X-ray energy spectrum-based Co element area profile of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0056] FIG. 15D shows an X-ray energy spectrum-based Cr element area profile of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0057] FIG. 15E shows an X-ray energy spectrum-based Ti element area profile of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0058] FIG. 15F shows an X-ray energy spectrum-based Fe element area profile of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0059] FIG. 15G shows an X-ray energy spectrum-based Ni element area profile of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3;

[0060] FIG. 15H shows an X-ray energy spectrum-based Cu element area profile of the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in Example 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0061] In order to make the present disclosure more understandable, preferred examples are provided to describe in detail as follows.

[0062] In each example, tests and equipment involved are as follows:

[0063] a high vacuum non-consumable arc smelting furnace: an NF-800 high vacuum non-consumable arc smelting furnace produced by Deyang Aona New Material Co., Ltd. in Sichuan, China;

[0064] microstructure: metallographic observation is conducted using an Axio Observer D1M inverted metallographic microscope produced by Carl Zeiss; a metallographic sample has a size of 5 mm×5 mm×5 mm; the sample is inlaid with phenolic resin, and then polished with 400#, 600#, 1000#, 1500#, and 3000# silicon carbide sandpapers in sequence, and then polished using a diamond polishing paste with a particle size of 1.5 μm; a scanning electron microscope is a Gemini 300 field-emission scanning electron microscope produced by Carl Zeiss, and an X-ray energy dispersive analysis is conducted by an X-Max large-area electric cooling energy spectral detection system produced by Oxford Instruments; and

[0065] Quasi-static tensile mechanical properties test: according to a standard GB/T228.1-2010, axial quasi-static tensile test at room temperature was conducted using a Zwick Z020 microcomputer-controlled electronic universal testing machine, where a strain rate is selected as 10.sup.−3 s.sup.−1, and a test sample is a non-standard I-shaped piece, with a thickness of 1.20 mm, a length of 61 mm, a gauge length of 15.00 mm, and a gauge length of 5.00 mm.

EXAMPLE 1

[0066] A high-strength and high-plasticity casting HEA had a general formula of Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6.

[0067] A preparation method included the following steps:

[0068] step 1, pre-preparation of a sample:

[0069] high-purity particles of Al, Co, Cr, Cu, Fe, Ni, and Ti elementary substances each with a purity of not less than 99.95% were completely cleaned with ultrasonic acetone, and air-dried after cleaning; and clean raw materials with a total mass of 500.00 g±0.02 g were accurately weighed using an analytical balance and according to an atomic ratio of Al, Co, Cr, Ti, Fe, Ni and Cu at 7.6:21.7:10.9:5.2:21.7:32.3:0.6;

[0070] step 2, alloy melting:

[0071] cleaned high-purity metal raw materials Al, Co, Cr, Cu, Fe, Ni, and Ti were put into an inner working position of an electric arc smelting furnace, and a vacuum hood of the electric arc furnace was closed; a valve of an oil-sealed mechanical pump was opened, and the furnace was vacuumized using the oil-sealed mechanical pump to not more than 3.0×10.sup.0 Pa; the valve of the oil-sealed mechanical pump was closed; a valve of a turbo molecular pump was opened, and the furnace was vacuumized using the turbo molecular pump to less than 6.0×10.sup.−4 Pa; the turbo molecular pump valve was closed, a protective gas filling valve was opened, and the vacuum hood was filled with high-purity argon in a purity of 99.999% to complete the vacuumizing and filling; and

[0072] alloy smelting was conducted: the alloys were put into stations of the smelting furnace separately, the metal Ti was smelted for deoxidation, and the rest of the metals were added for melting in the high-vacuum smelting furnace; after all the metals were melted, electromagnetic stirring was conducted to make a melt fully stirred; during the smelting, an alloy ingot was subjected to overturning type smelting 5 times with about 5 min in each time; and

[0073] step 3, after the smelting was completed, an alloy obtained in step 2 was poured into a square water cooling plate-shaped copper mold for casting, cooled to room temperature to obtain the HEA.

[0074] A casting HEA with dimensions of 100 mm×100 mm×6 mm was obtained from a casting plate of the casting HEA prepared in step 3 by wire EDM and milling.

[0075] Experimental test and analysis:

[0076] The Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA prepared in this example was used as a test sample for experimental inspection. According to tensile test results in FIG. 2, the Al.sub.7.6Co.sub.21.7Cr.sub.10.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA has a tensile strength of 1071 MPa and an elongation at break of 19.5%. It can be seen from a metallographic structure in FIG. 3 that the Al.sub.7.6Co.sub.21.7Cr.sub.0.9Ti.sub.5.2Fe.sub.21.7Ni.sub.32.3Cu.sub.0.6 casting HEA is mainly composed of FCC and L.sub.12 phases, with a uniformly-distributed casting dendritic structure. From a scanning electron microscope image in FIG. 4 and an element area profile in FIGS. 5A-5H, it can be seen that elements Co, Cr, Fe, and Ni are distributed in a dendrite region, while elements Cu, Al, and Ti are distributed in an interdendritic region.

EXAMPLE 2

[0077] A high-strength and high-plasticity casting HEA had a general formula of Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5.

[0078] A preparation method included the following steps:

[0079] step 1, pre-preparation of a sample:

[0080] high-purity particles of Al, Co, Cr, Cu, Fe, Ni, and Ti elementary substances each with a purity of not less than 99.95% were completely cleaned with ultrasonic acetone, and air-dried after cleaning; and clean raw materials with a total mass of 500.00 g±0.02 g were accurately weighed using an analytical balance and according to an atomic ratio of Al, Co, Cr, Ti, Fe, Ni and Cu at 7.3:21.4:10.6:4.9:21.4:31.9:2.5;

[0081] step 2, alloy melting:

[0082] cleaned high-purity metal raw materials Al, Co, Cr, Cu, Fe, Ni, and Ti were put into an inner working position of an electric arc smelting furnace, and a vacuum hood of the electric arc furnace was closed; a valve of an oil-sealed mechanical pump was opened, and the furnace was vacuumized using the oil-sealed mechanical pump to not more than 3.0×10.sup.0 Pa; the valve of the oil-sealed mechanical pump was closed; a valve of a turbo molecular pump was opened, and the furnace was vacuumized using the turbo molecular pump to less than 6.0×10.sup.−4 Pa; the turbo molecular pump valve was closed, a protective gas filling valve was opened, and the vacuum hood was filled with high-purity argon in a purity of 99.999% to complete the vacuumizing and filling; and

[0083] alloy smelting was conducted: the alloys were put into stations of the smelting furnace separately, the metal Ti was smelted for deoxidation, and the rest of the metals were added for melting in the high-vacuum smelting furnace; after all the metals were melted, electromagnetic stirring was conducted to make a melt fully stirred; during the smelting, an alloy ingot was subjected to overturning type smelting 5 times with about 5 min in each time; and

[0084] step 3, after the smelting was completed, an alloy obtained in step 2 was poured into a square water cooling plate-shaped copper mold for casting, cooled to room temperature to obtain the HEA.

[0085] A casting HEA with dimensions of 100 mm×100 mm×6 mm was obtained from a casting plate of the casting HEA prepared in step 3 by wire EDM and milling.

[0086] Experimental test and analysis:

[0087] The Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA prepared in this example was used as a test sample for experimental inspection. According to tensile test results in FIG. 7, the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA has a tensile strength of 955 MPa and an elongation at break of 16.5%. It can be seen from a metallographic structure in FIG. 8 that the Al.sub.7.3Co.sub.21.4Cr.sub.10.6Ti.sub.4.9Fe.sub.21.4Ni.sub.31.9Cu.sub.2.5 casting HEA is mainly composed of FCC and L.sub.12 phases, with a uniformly-distributed casting dendritic structure. From a scanning electron microscope image in FIG. 9 and an element area profile in FIGS. 10A-10H, it can be seen that elements Co, Cr, Fe, and Ni are distributed in a dendrite region, while elements Cu, Al, and Ti are distributed in an interdendritic region.

EXAMPLE 3

[0088] A high-strength and high-plasticity casting HEA had a general formula of Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0.

[0089] A preparation method included the following steps:

[0090] step 1, pre-preparation of a sample:

[0091] high-purity particles of Al, Co, Cr, Cu, Fe, Ni, and Ti elementary substances each with a purity of not less than 99.95% were completely cleaned with ultrasonic acetone, and air-dried after cleaning; and clean raw materials with a total mass of 500.00 g±0.02 g were accurately weighed using an analytical balance and according to an atomic ratio of Al, Co, Cr, Ti, Fe, Ni and Cu at 7.2:20.7:10.4:4.8:20.7:31.2:5.0;

[0092] step 2, alloy melting:

[0093] cleaned high-purity metal raw materials Al, Co, Cr, Cu, Fe, Ni, and Ti were put into an inner working position of an electric arc smelting furnace, and a vacuum hood of the electric arc furnace was closed; a valve of an oil-sealed mechanical pump was opened, and the furnace was vacuumized using the oil-sealed mechanical pump to not more than 3.0×10.sup.0 Pa; the valve of the oil-sealed mechanical pump was closed; a valve of a turbo molecular pump was opened, and the furnace was vacuumized using the turbo molecular pump to less than 6.0×10.sup.−4 Pa; the turbo molecular pump valve was closed, a protective gas filling valve was opened, and the vacuum hood was filled with high-purity argon in a purity of 99.999% to complete the vacuumizing and filling; and

[0094] alloy smelting was conducted: the alloys were put into stations of the smelting furnace separately, the metal Ti was smelted for deoxidation, and the rest of the metals were added for melting in the high-vacuum smelting furnace; after all the metals were melted, electromagnetic stirring was conducted to make a melt fully stirred; during the smelting, an alloy ingot was subjected to overturning type smelting 5 times with about 5 min in each time; and

[0095] step 3, after the smelting was completed, an alloy obtained in step 2 was poured into a square water cooling plate-shaped copper mold for casting, cooled to room temperature to obtain the HEA.

[0096] A casting HEA with dimensions of 100 mm×100 mm×6 mm was obtained from a casting plate of the casting HEA prepared in step 3 by wire EDM and milling.

[0097] Experimental test and analysis:

[0098] The Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA prepared in this example was used as a test sample for experimental inspection. According to tensile test results in FIG. 12, the Al.sub.7.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA has a tensile strength of 906 MPa and an elongation at break of 13.1%. It can be seen from a metallographic structure in FIG. 13 that the Al.sub.17.2Co.sub.20.7Cr.sub.10.4Ti.sub.4.8Fe.sub.20.7Ni.sub.31.2Cu.sub.5.0 casting HEA is mainly composed of FCC and L.sub.12 phases, with a uniformly-distributed casting dendritic structure. From a scanning electron microscope image in FIG. 14 and an element area profile in FIGS. 15A-15H, it can be seen that elements Co, Cr, Fe, and Ni are distributed in a dendrite region, while elements Cu, Al, and Ti are distributed in an interdendritic region.

[0099] In summary, the present disclosure provides a high-strength and high-plasticity casting HEA, and a preparation method thereof that is simple and easy to implement. By designing the composition and using a simple vacuum casting technology, HEAs with high strength and desirable plasticity can be obtained by industrial production. The HEA has a casting dendritic structure, with an excellent tensile strength and desirable plasticity, and has extremely broad prospects for use in the engineering field. The present disclosure further discloses a preparation method of the HEA. The high-strength and high-plasticity casting HEA with excellent mechanical properties can be obtained by only one-step casting. The preparation method is simple and safe, which can meet industrial production conditions.