CN112011712B

CN112011712B - Component formula and preparation process of light refractory high-entropy alloy

Info

Publication number: CN112011712B
Application number: CN202010817989.0A
Authority: CN
Inventors: 贾延东; 贾岳飞; 王刚; 易军; 翟启杰
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2022-05-27
Anticipated expiration: 2040-08-14
Also published as: CN112011712A

Abstract

The application discloses a component formula and a preparation process of a light refractory high-entropy alloy, wherein the alloy formula comprises Nb, Ti, V, Zr and Mo elements, and the molar ratio of the Nb to the Ti to the V to the Zr to the Mo is =1:3:2:1: 0.1. The alloy raw material consists of Nb, Ti, V, Zr and Mo elements, is placed into a vacuum arc melting furnace for melting, and is melted under the state of a preset atmosphere; sucking the solution into a preset plate-shaped water-cooling copper mold by adopting a copper mold suction casting method to obtain an alloy product; placing the alloy product into a vacuum heat treatment furnace, and carrying out homogenization treatment at a first preset temperature for a first preset time; carrying out cold rolling treatment on the alloy product subjected to homogenization treatment for a plurality of times to obtain a rolled product with the final rolling thickness; and putting the alloy product into a vacuum heat treatment furnace, and annealing at a second preset temperature for a second preset time. The invention has the beneficial effects of providing a new formula of the light refractory high-entropy alloy with excellent performance and corresponding preparation and treatment processes.

Description

Component formula and preparation process of light refractory high-entropy alloy

Technical Field

The invention relates to a component formula and a preparation process of an alloy, in particular to a component formula and a preparation process of a refractory high-entropy alloy.

Background

The metal material is widely applied to various industries of society as an engineering structure material. However, with the rapid development of science and technology, the requirements for metal materials are also increased, and more excellent performance, higher reliability and lower cost are required. The concept of traditional alloys based on a single principal element and microalloying limits more possibilities for alloy property development. Therefore, the embarrassment situation of the traditional alloy is broken through by the high-entropy alloy. The design idea of the high-entropy alloy multi-principal element alloy enables the alloy to have more possibilities in structure and performance. At present, the discovered high-entropy alloy has the characteristics of high strength, high toughness, excellent fatigue resistance, excellent corrosion resistance, good thermal stability and the like.

The refractory high-entropy alloy is used as one of a plurality of high-entropy alloys, has the characteristics of high strength, high-temperature strength and the like, and has great application value in the field of high-temperature materials. However, such alloys also have disadvantages, for example, they generally have no or relatively poor tensile plasticity, for example, NbMoTaW, NbMoTaWV, NbMoTaWTi, etc. have relatively poor plastic deformability. This deficiency limits the range of engineering applications for such alloys to a large extent. Such alloys typically have relatively high densities and relatively high costs, such as HfNbTiZr, HfNbTaTiZr, and the like, with alloys having densities of about 10 g/cm³And since the constituent elements Hf, Ta, Nb, etc. have relatively high prices, such alloys are relatively high in cost.

In order to solve these problems of high entropy of refractory, some researchers add light elements such as Al, Si, and C to modify the alloy, and although the density and cost are reduced, the tensile plasticity of the alloy is also sharply reduced. Thus, these relatively troublesome problems remain with the development of refractory high entropy alloys to date. How to obtain refractory high-entropy alloy with tensile plasticity and relatively low density, low cost and high strength is urgently needed.

Disclosure of Invention

A component formula and a preparation process of a light refractory high-entropy alloy are disclosed, wherein the preparation method comprises the following steps: preparing alloy raw materials according to preset mass parts, wherein the alloy raw materials consist of Nb, Ti, V and Zr elements; putting the alloy raw material into a vacuum arc melting furnace for melting, wherein the vacuum arc melting furnace is in a preset atmosphere state for melting; sucking the solution into a preset plate-shaped water-cooling copper mold by adopting a copper mold suction casting method to obtain an alloy product; placing the alloy product into a vacuum heat treatment furnace, and carrying out homogenization treatment at a first preset temperature for a first preset time; carrying out cold rolling treatment on the alloy product subjected to homogenization treatment for a plurality of times to obtain a rolled product with the final rolling thickness; placing the alloy product into a vacuum heat treatment furnace, and annealing at a second preset temperature for a second preset time; wherein the preset mass fraction of the alloy raw materials has the value range as follows: nb: 20 to 22; ti: 32 to 34; v: 22 to 24; zr: 20 to 22; mo: 0 to 5.

Furthermore, the elements of the alloy raw materials are Nb, Ti, V, Zr and Mo =1:3:2:1:0.1 according to the atomic ratio.

Further, the first preset temperature ranges from 1000 ℃ to 1300 ℃.

Further, the value range of the first preset time is 3 hours to 5 hours.

Further, the second preset temperature ranges from 700 ℃ to 900 ℃.

Further, the second preset time period ranges from 0.5 hour to 1.5 hours.

Further, the preset atmosphere is an argon atmosphere.

Further, the alloy raw material is melted in the vacuum arc melting furnace for several times.

The invention has the advantages that:

provides a component formula and a preparation process for preparing light refractory high-entropy alloy with excellent performance.

Drawings

FIG. 1 is a diagram of the process of preparing a draw sample in accordance with an embodiment of the present invention.

FIG. 2 is a comparison of the tensile curves for Nb to Ti to V to Zr to Mo =1:3:2:1:0.1 for a specific example of the invention versus the tensile curves for the refractory high entropy alloys HfNbTaTiZr and NbTiVZr and commercial Ti6Al 4V;

FIG. 3 is an X-ray diffraction analysis of Nb, Ti, V, Zr, Mo =1:3:2:1:0.1 in an embodiment of the invention with the abscissa

Angle (°); the ordinate is intensity after normalization;

FIG. 4 is an observation of the microstructure of a specific example of the invention Nb: Ti: V: Zr: Mo =1:3:2:1:0.1 (FIG. 4a, observed using the back-scattering mode of EPMA) and the corresponding grain size statistics (FIG. 4 b);

FIG. 5 shows a microstructure of an embodiment of the present invention (observed using the back-scattering mode of EPMA) of Nb: Ti: V: Zr: Mo =1:3:2:1: 0.1;

FIG. 6 is a graph showing the line distribution of the microstructure and elements of a specific example of the present invention Nb: Ti: V: Zr: Mo =1:3:2:1:0.1 (FIG. 6(a) observed by a back-scattering mode of EPMA, and FIG. 6(b) obtained by line scan analysis using an EPMA apparatus);

Detailed Description

The present invention will be described in detail with reference to examples

The components of examples 1 to 4 were proportioned as shown in the following table.

Step 1: the component proportion of the alloy is very critical, the corresponding atomic percentage and mass percentage are calculated according to the atomic proportion relation among the alloy components, and meanwhile, the theoretical density of the alloy can be calculated by utilizing a mixing rule. The following table gives examples of the results of calculations for some of the alloy compositions. And proportioning the alloy raw materials according to the calculated result.

Step 2: selecting raw materials with the purity of 99.9%, cleaning dirty objects such as oxide skins on the surfaces of the raw materials, then ultrasonically cleaning the raw materials by acetone, and drying the raw materials by a blower. According to the above calculation results, weighing was performed using a balance with accuracy (0.001).

And step 3: putting the prepared raw materials into a water-cooled non-consumable vacuum arc melting furnace according to the sequence that the melting point is from low to high and the size is from small to large, vacuumizing to below 0.005Pa, filling high-purity argon, flushing the furnace chamber, repeating for three times, opening an electric arc under the protection of the high-purity argon to enable the initial current of the electric arc to be 60-80A, gradually increasing to about 150A, and melting a titanium ingot; and then moving to the raw material to be smelted, gradually smelting the prepared raw material along a water-cooled copper crucible, increasing the current to 200A, and staying for about 10s to melt the alloy into a button ingot. Then, after the smelting is repeated for 2 times, the electromagnetic stirring function of the electric arc is turned on to carry out the third smelting, the alloy can be smelted more uniformly by the electric arc stirring, and the part difficult to be smelted in the electric arc can be fully smelted and diffused along with the stirring. And (4) repeatedly melting for two times, closing the electromagnetic stirring, melting for one time again, and ensuring at least five times to ensure that the alloy components are fully melted and uniformly diffused.

And 4, step 4: by adopting a copper mold suction casting method, the fully smelted refractory high-entropy alloy is kept for 10-20 seconds when the electric arc of the electric arc is 300-400A, and then the melt can be sucked into a designed plate-shaped water-cooling copper mold (with the width of 10 mm, the thickness of 3 mm and the height of 80 mm) to obtain a corresponding plate-shaped sample with the thickness of 3 mm.

As a specific scheme, the preparation method of the present application comprises:

step 1: and (3) obtaining a plate-shaped refractory high-entropy sample with the thickness of 3 mm, placing the sample in a vacuum heat treatment furnace (the vacuum degree is less than 0.005 Pa), carrying out homogenization treatment, keeping the temperature at 1200 ℃ for 4h, and then cooling the sample to room temperature in air.

And 2, step: and (4) carrying out multi-pass cold rolling on the homogenized sample to 0.5 mm.

And step 3: and (3) carrying out recrystallization annealing on the rolled sample, placing the sample in a vacuum heat treatment furnace (the vacuum degree is less than 0.005 Pa), heating to 800 ℃, annealing for 1 h, and air cooling to room temperature.

And 4, step 4: the rolled and heat treated sample was wire cut to give the drawn sample of fig. 1.

And (3) performing tensile mechanical test on the tensile sample prepared by the method:

the tensile test is completed on an MTS-CMT5205 universal mechanics experiment machine, the gauge length of a tensile sample is 12.7mm, the gauge length of an extensometer is 12mm, and the strain rate is 0.001s^-1. The tensile test result of the refractory high-entropy alloy (NbTi3V2ZrMo0.1) after cold rolling and annealing is shown in figure 2. The yield strength of the refractory high-entropy alloy NbTi3V2ZrMo0.1 exceeds 1 GPa and is 1040 MPa, and the tensile strength reaches 1257 MPa. The tensile strain of the refractory high-entropy alloy exceeds 20 percent, and the refractory high-entropy alloy has relatively good tensile plastic deformation capability.

The crystal structures of the prepared series of refractory high-entropy alloys are characterized:

the crystal structure of the alloy is characterized by X-ray diffraction, the scanning angle is 10-90 degrees, and the scanning speed is 4 degrees/min. Fig. 3 is an X-ray diffraction pattern of a refractory high-entropy alloy of Nb: Ti: V: Zr: Mo =1:3:2:1: 0.1. FIG. 3 illustrates that the phase composition of the high-entropy alloy is mainly BCC structural phase (indicated by diamonds in the figure) and contains part of second phase (indicated by black peaches in the figure).

The microstructure of the prepared refractory high-entropy alloy NbTi3V2ZrMo0.1 is characterized:

the microstructure and composition analysis of the alloy were carried out by using EPMA manufactured by Shimadzu corporation of Japan. FIG. 4 reflects the grain size of the refractory high entropy alloy NbTi3V2ZrMo0.1. The average grain size of the alloy nbti3v2zrmo0.1 was about 21 microns. Fig. 5 reflects a more uniform distribution of second phase particles in the alloy. Fig. 6(a) reflects the size of the second phase particles, about 300 nm, and fig. 6(b) reflects that the second phase is a Zr rich phase with a higher Zr content. The precipitated phase can be judged by combining the tensile property of the alloy NbTi3V2ZrMo0.1 in the figure 2, and the great contribution is made to the excellent mechanical property of the alloy.

The invention mainly focuses on the problems of low tensile plasticity, high density and high cost of the refractory high-entropy alloy. The invention utilizes common elements Nb, Ti, V, Zr, Mo and the like of the refractory high-entropy alloy to carry out component regulation and control in different proportions, cold rolling and other processes, finally obtains a series of refractory high-entropy alloys with better tensile plasticity, lower cost, lower density and higher strength, and breaks through the current situations of low tensile plasticity, high density and high cost of the refractory high-entropy alloys.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.

Claims

1. A preparation process of a light refractory high-entropy alloy is characterized by comprising the following steps:

the preparation process comprises the following steps:

preparing alloy raw materials according to preset mass parts, wherein the alloy raw materials consist of Nb, Ti, V, Zr and Mo elements;

the molar ratio of the raw materials is Nb, Ti, V, Zr and Mo, is 1:3:2:1: 0.1;

putting the alloy raw material into a vacuum arc melting furnace for melting, wherein the vacuum arc melting furnace is in a preset atmosphere state for melting;

sucking the solution into a preset plate-shaped water-cooling copper mold by adopting a copper mold suction casting method to obtain an alloy product;

placing the alloy product into a vacuum heat treatment furnace, and carrying out homogenization treatment at a first preset temperature for a first preset time;

carrying out cold rolling treatment on the alloy product subjected to homogenization treatment for a plurality of times to obtain a rolled product with the final rolling thickness;

placing the alloy product into a vacuum heat treatment furnace, and annealing at a second preset temperature for a second preset time;

the value range of the first preset temperature is 1000-1300 ℃;

the value range of the first preset time is 3 hours to 5 hours;

the value range of the second preset temperature is 700-900 ℃;

the value range of the second preset time is 0.5 to 1.5 hours;

the preset atmosphere is argon atmosphere;

the alloy raw material is smelted in the vacuum arc smelting furnace for a plurality of times.