A high-density high-strength multi-phase high-entropy alloy and a preparation method thereof

Abstract

The application relates to a high-density high-strength three-phase high-entropy alloy and a preparation method thereof, and belongs to the high-entropy alloy field. In order to obtain high density and high strength, the new alloy introduces the concept of a multiphase structure, and a high-entropy alloy with a multiphase structure is designed. The alloy is composed of W, Ta, Hf, Nb and Ni elements, and has BCC, FCC and HCP phases. The new alloy has high strength, the yield strength under the condition of quasi-static compression at room temperature is greater than 1400 MPa, the compressive strength is greater than 2600 MPa, the fracture strain is about 20%, and the density is between 14 and 15 g / cm 3 .

Description

TECHNICAL FIELD

[0001] The application relates to a high-density high-strength multiphase high-entropy alloy and a preparation method thereof, in particular to a W a Ta b Hf c Nb d Ni e high-entropy alloy material and a preparation method thereof, and belongs to the field of high-entropy alloys. BACKGROUND

[0002] In anti-armor applications, heavy tungsten alloy and depleted uranium (DU) alloy are two major materials. Due to the extremely high density and mechanical properties, DU kinetic energy penetrator shows excellent penetration performance in the penetration process, but causes serious environmental pollution. Compared with the DU alloy, the tungsten alloy kinetic energy penetrator has poor strength and ductility and insufficient penetration performance. Therefore, a high-performance tungsten alloy needs to be developed to replace the DU alloy.

[0003] High-entropy alloy is a new alloy design concept proposed in the past decade. Compared with the traditional alloy with only one or two main elements, the high-entropy alloy has multiple main elements. The multiple main element characteristics make the high-entropy alloy have structural lattice distortion effect, high-entropy effect in thermodynamics, hysteresis diffusion effect in dynamics, and cocktail effect in performance. These effects make the high-entropy alloy have great application potential in the fields of aerospace, protection, biology, kinetic energy penetrator and the like. Therefore, in recent years, the high-entropy alloy has become a research hotspot in the alloy field. In order to have higher penetration performance, the kinetic energy penetrator material needs to have higher density, but the performance of the high-density high-entropy alloy is still far from that of the heavy tungsten alloy. Therefore, it is urgent to invent a high-entropy alloy with high density and high strength. SUMMARY

[0004] The application aims to solve the problem of low strength and ductility of the existing high-density high-entropy alloy, and provides a high-density high-strength multiphase high-entropy alloy and a preparation method thereof. The alloy W a Ta b Hf c Nb d Ni e is prepared by arc melting.

[0005] The application is achieved by the following technical scheme.

[0006] A high-density high-strength multiphase high-entropy alloy is composed of W, Ta, Hf, Nb and Nb five elements W a Ta b Hf c Nb d Ni eThe components, a, b, c, d, and e are atomic percentages of five elements, wherein 30<=a<=45, 20<=b<=30, 10<=c<=25, 10<=d<=25, 10<=e<=25, and a+b+c+d+e=100;

[0007] A preparation method of a high-density high-strength multi-phase high-entropy alloy, comprising the following steps:

[0008] Step one: five elements of W, Ta, Hf, Nb and Ni are selected, accurately weighed according to atomic percentage, and sequentially placed into a copper crucible of a non-consumable vacuum arc melting furnace according to the order from low to high melting point, i.e. Ni, Hf, Nb, Ta and W.

[0009] Step two: the furnace door is closed, the non-consumable vacuum arc melting furnace is pumped to a vacuum state, and then high-purity argon gas with a purity of 99.99wt% is introduced as a protective gas.

[0010] Step three: W a Ta b Hf c Nb d Ni e alloy is melted, the melting is carried out until the alloy is completely melted and uniformly mixed, then the master alloy button ingot is turned over by a mechanical hand after cooling, and the next melting is carried out by the same method, and a total of ten times of melting are carried out. During the second to ninth times of melting, the magnetic stirring is started to make the high-entropy alloy master alloy ingot more uniform.

[0011] Step four: after W a Ta b Hf c Nb d Ni e alloy melting is completed, the copper mold is cooled to room temperature, the furnace door is opened, and the sample is taken out to obtain W a Ta b Hf c Nb d Ni e alloy.

[0012] Beneficial effects

[0013] 1. The high-density high-strength multi-phase high-entropy alloy material of the application is composed of W a Ta b Hf c Nb d Ni e , and the high-entropy alloy with a multi-phase structure is prepared by a vacuum non-consumable arc melting furnace. The W a Ta b Hf c Nbd Ni e The alloy has high density and high strength.

[0014] 2. The high-density high-strength multi-phase high-entropy alloy material of the present application, SEM and EDS test results show that BCC+FCC+HCP. a Ta b Hf c Nb d Ni e The alloy has high density, high quasi-static compression yield strength, and fracture strength. The density of the alloy is 14 g / cm 3 ~ 15 g / cm 3 The yield strength of the alloy under quasi-static compression at room temperature is above 1400 MPa, the compressive strength is above 2600 MPa, and the fracture strain is about 20%, which is greater than the strength of most high-density high-entropy alloys. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 SEM backscattering image of the alloy; wherein, Figure a is a low-magnification SEM image; Figure b is a high-magnification SEM image;

[0016] Figure 2 W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 XRD image of the alloy;

[0017] Figure 3 W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 Quasi-static compression stress-strain curve of the alloy at room temperature;

[0018] Figure 4 W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 Dynamic compression stress-strain curve of the alloy at room temperature. DETAILED DESCRIPTION

[0019] The present application will be further described below in conjunction with the drawings and examples.

[0020] Example 1

[0021] A high-density high-strength multi-phase high-entropy alloy material, which is composed of W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 Alloy, the alloy is composed of BCC+FCC+HCP, as Figure 4 shown.

[0022] The W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 High-entropy alloy material, characterized in that it comprises the following steps:

[0023] Step one: select W, Ta, Hf, Nb, Ni five elements, accurately weigh according to atomic percentage, and according to the order of low to high melting point, namely Ni, Hf, Nb, Ta, W, put into the copper crucible of non-consumable vacuum arc furnace in turn.

[0024] Step two: close the door, and then introduce high-purity argon gas with a purity of 99.99wt% as protective gas.

[0025] Step three: melt the W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 Alloy, melt until the alloy is completely melted and uniformly mixed, then turn the master alloy button ingot after cooling, and perform the next melting by the same method, a total of ten times. Among them, the second to ninth times of melting, need to open the magnetic stirring, make the high-entropy alloy ingot more uniform.

[0026] Step four: after the W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 Alloy melting is finished, the copper mold is cooled to room temperature, the door is opened, and the sample is taken out, to obtain W 33.3 Ta 22.2 Hf 16.7 Nb 11.1 Ni 16.7 Alloy.

[0027] The alloy is subjected to quasi-static compression and dynamic compression mechanical property test at room temperature, as Figure 1 , 2 shown. The experiment shows that the density of the alloy is 14g / cm 3~15 g / cm 3 The yield strength of the alloy is above 1400 MPa, the compressive strength is above 2600 MPa, and the fracture strain is about 20% at room temperature under quasi-static compression; the yield strength of the alloy is 1700 MPa, the compressive strength is above 2400 MPa, and the fracture strain is 29% at a strain rate of 4000 s -1 The yield strength of the alloy is above 1400 MPa, the compressive strength is above 2600 MPa, and the fracture strain is about 20% at room temperature under quasi-static compression; the yield strength of the alloy is 1700 MPa, the compressive strength is above 2400 MPa, and the fracture strain is 29% at a strain rate of 4000 s

[0028] Embodiment 2

[0029] A high-density high-strength multi-phase high-entropy alloy material, which is composed of W 35 Ta 10 Hf 15 Nb 25 Ni 15 The alloy is composed of BCC+FCC+HCP.

[0030] The W 35 Ta 10 Hf 15 Nb 25 Ni 15 High-entropy alloy material, characterized in that it comprises the following steps:

[0031] Step 1: five elements of W, Ta, Hf, Nb and Ni are selected, accurately weighed according to the atomic percentage, and sequentially placed in the copper crucible of the non-consumable vacuum arc melting furnace in the order of Ni, Hf, Nb, Ta and W according to the melting point from low to high.

[0032] Step 2: close the furnace door, and then introduce high-purity argon gas with a purity of 99.99wt% as a protective gas after the non-consumable vacuum arc melting furnace is pumped to a vacuum state.

[0033] Step 3: the W 35 Ta 10 Hf 15 Nb 25 Ni 15 Alloy is melted, and the alloy is melted and mixed uniformly until the master alloy button ingot is cooled, then the master alloy is turned over by a mechanical hand, and the next melting is carried out by the same method, a total of ten times of melting. Among them, during the second to ninth melting, the magnetic stirring is started to make the high-entropy alloy master alloy ingot more uniform.

[0034] Step 4: after the W 35 Ta 10 Hf 15 Nb 25 Ni 15 Alloy melting is finished, the copper mold is cooled to room temperature, the furnace door is opened, and the sample is taken out to obtain the W 35 Ta10 Hf 15 Nb 25 Ni 15 alloy.

[0035] The alloy is subjected to quasi-static compression and dynamic compression mechanical property test at room temperature, and experiments show that the density of the alloy is 14 g / cm 3 ~ 15 g / cm 3 . The yield strength of the alloy under quasi-static compression at room temperature is above 1300 MPa, the compressive strength is above 2550 MPa, and the fracture strain is about 20%; at a strain rate of 4000 s -1 , the yield strength is 1600 MPa, the compressive strength is above 2300 MPa, and the fracture strain is 30%. Far exceeding most refractory high-entropy alloys.

[0036] Embodiment 3

[0037] A high-density high-strength multi-phase high-entropy alloy material, which is composed of W 30 Ta 20 Hf 15 Nb 20 Ni 15 alloy, the alloy is composed of BCC+FCC+HCP.

[0038] The W 30 Ta 20 Hf 15 Nb 20 Ni 15 high-entropy alloy material, characterized in that it comprises the following steps:

[0039] Step 1: five elements of W, Ta, Hf, Nb and Ni are selected, accurately weighed according to the atomic percentage, and sequentially placed in the copper crucible of the non-consumable vacuum arc melting furnace according to the order from low to high melting point, i.e. Ni, Hf, Nb, Ta and W.

[0040] Step 2: close the furnace door, and then introduce high-purity argon gas with a purity of 99.99wt% as a protective gas after the non-consumable vacuum arc melting furnace is pumped to a vacuum state.

[0041] Step 3: the W 30 Ta 20 Hf 15 Nb 20 Ni 15 alloy is melted, and the melting is continued until the alloy is completely melted and uniformly mixed, then the master alloy button ingot is turned over by a mechanical hand after cooling, and the next melting is carried out by the same method, a total of ten times of melting. Among them, during the second to ninth melting, the magnetic stirring is started to make the high-entropy alloy ingot more uniform.

[0042] Step four: W 30 Ta 20 Hf 15 Nb 20 Ni 15 The alloy smelting is finished, the copper mold is cooled to room temperature, the furnace door is opened, the sample is taken out, and the W 30 Ta 20 Hf 15 Nb 20 Ni 15 alloy.

[0043] The quasi-static compression and dynamic compression mechanical property test of the alloy at room temperature is carried out, and experiments show that the density of the alloy is 14 g / cm 3 ~ 15 g / cm 3 . The yield strength of the quasi-static compression of the alloy at room temperature is above 1200 MPa, the compressive strength is above 2500 MPa, and the fracture strain is about 20%; at a strain rate of 4000 s -1 , the yield strength is 1620 MPa, the compressive strength is above 2200 MPa, and the fracture strain is 28%. Far more than most refractory high-entropy alloys.

[0044] The above is the description of the preferred embodiments of the present application. Here, it should be noted that the present application is not limited to the above embodiments, and any modification, equivalent replacement or improvement made to the present application within the scope of the claims, the summary of the invention and the drawings should be included in the protection scope of the present application.

Claims

1. A high-density high-strength multi-phase high-entropy alloy, characterized in that: W, Ta, Hf, Nb and Ni a Ta b Hf c Nb d Ni e a, b, c, d, e are atomic percentages of the five elements respectively; wherein, 30≤a≤45, 20≤b≤30, 10≤c≤25, 10≤d≤25, 10≤e≤25, a+b+c+d+e=100.

2. The method for preparing the high-density high-strength multi-phase high-entropy alloy according to claim 1, characterized in that: The specific steps are as follows: Step one: five elements of W, Ta, Hf, Nb and Ni are selected, accurately weighed according to the atomic percentage, and sequentially put into the copper crucible of the non-consumable vacuum arc melting furnace according to the order from low to high melting point, i.e. Ni, Hf, Nb, Ta and W; Step two: close the furnace door, and vacuumize the non-consumable vacuum arc melting furnace, and then introduce high-purity argon gas with a purity of 99.99wt% as a protective gas; Step three: melting the W a Ta b Hf c Nb d Ni e The alloy is melted until the alloy is completely melted and uniformly mixed, and then after the master alloy button ingot is cooled, the master alloy is turned over by a mechanical hand, and the next melting is carried out by the same method, a total of ten times of melting; wherein during the second to ninth times of melting, magnetic stirring is started to make the high-entropy alloy master alloy ingot more uniform. Step four: The W a Ta b Hf c Nb d Ni e alloy melting is finished, the copper mold is cooled to room temperature, the furnace door is opened, and the sample is taken out to obtain the W a Ta b Hf c Nb d Ni e alloy.

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