阅读说明：本技术 一种低密度低膨胀高熵高温合金及其制备方法 (Low-density low-expansion high-entropy high-temperature alloy and preparation method thereof ) 是由 薛佳宁 于敏 安宁 张志伟 徐明舟 李振瑞 张�荣 于 2021-07-30 设计创作，主要内容包括：本发明属于合金材料领域,提供了一种低密度低膨胀高熵高温合金及其制备方法。所述合金的化学成分以质量分数计为：C：0.02-0.10％,Cr：20.5-25.0％,Co：8.0-11.0％,Mo：2.0-2.8％,Nb：2.0-3.8％,W：0.8-2.0％,Fe：9.0-15.0％,Al：1.0-4.0％,Ti：2.5-6.0％,余量为Ni及不可避免杂质元素；所述合金材料的显微组织主要为稳定的γ/γ'两相组织；通过合理设计合金元素成分,添加Al、Ti等低密度合金元素,使合金密度显著降低,具有≤8.0g/cm3的低密度,并降低了合金的成本,具有很好的结构减重效果；通过添加20.5-25.0％的Cr元素及1.0-4.0％的Al元素,在合金表面产生致密氧化膜,显著提高合金的耐蚀性；得到低膨胀,并兼顾高的高温强度、组织稳定性,以及良好加工性能的高熵高温合金。(The invention belongs to the field of alloy materials, and provides a low-density low-expansion high-entropy high-temperature alloy and a preparation method thereof. The alloy comprises the following chemical components in percentage by mass: c: 0.02-0.10%, Cr: 20.5-25.0%, Co: 8.0-11.0%, Mo: 2.0-2.8%, Nb: 2.0-3.8%, W: 0.8-2.0%, Fe: 9.0-15.0%, Al: 1.0-4.0%, Ti: 2.5-6.0%, and the balance of Ni and inevitable impurity elements; the microstructure of the alloy material is mainly a stable gamma/gamma' two-phase structure; by reasonably designing the components of alloy elements and adding low-density alloy elements such as Al, Ti and the like, the alloy density is obviously reduced, the low density of less than or equal to 8.0g/cm3 is achieved, the cost of the alloy is reduced, and the alloy has a good structure weight reduction effect; by adding 20.5-25.0% of Cr element and 1.0-4.0% of Al element, a compact oxidation film is generated on the surface of the alloy, and the corrosion resistance of the alloy is obviously improved; the high-entropy high-temperature alloy with low expansion, high-temperature strength, high structural stability and good processability is obtained.)

1. A low-density low-expansion high-entropy high-temperature alloy is characterized in that the chemical composition of the alloy comprises the following components in percentage by mass: c: 0.02-0.10%, Cr: 20.5-25.0%, Co: 8.0-11.0%, Mo: 2.0-2.8%, Nb: 2.0-3.8%, W: 0.8-2.0%, Fe: 9.0-15.0%, Al: 1.0-4.0%, Ti: 2.5-6.0%, and the balance of Ni and inevitable impurity elements; among the impurity elements, O is less than or equal to 0.005%, N is less than or equal to 0.005%, P is less than or equal to 0.015%, and S is less than or equal to 0.015%.

2. The alloy of claim 1, wherein the chemical composition of the alloy comprises, in mass fractions: : c: 0.02-0.08%, Cr: 20.5-23.0%, Co: 8.0-11.0%, Mo: 2.0-2.8%, Nb: 2.0-3.8%, W: 0.8-2.0%, Fe: 9.0-12.5%, Al: 1.0-3.0, Ti: 4.0-6.0 percent, and the balance of Ni and inevitable impurity elements.

3. The alloy of claim 1, wherein the sum of the mass fractions of Al and Ti is in the range of 6.5% to 9.5%.

4. The alloy of claim 1, wherein the alloy has a density of 8.0g/cm or less³(ii) a The alloy comprises a gamma/gamma 'two-phase structure, wherein the volume fraction of the gamma' phase reaches 40-60 percent, and the balance is the gamma phase and a small amount of impurity phase.

5. The alloy of claim 1, wherein the alloy has a coefficient of thermal expansion of 15 x 10 or less at 800 ℃^-6/K。

6. A method for producing a low-density low-expansion high-entropy high-temperature alloy according to any one of claims 1 to 5, wherein the method comprises:

obtaining a smelted alloy containing the chemical components;

performing first forging on the smelted alloy, and then remelting to obtain a remelted alloy;

performing secondary forging on the remelted alloy, wherein the temperature of the secondary forging is 950-1250 ℃, and then performing multiple forging forming to obtain a forged alloy;

and sequentially carrying out solid solution heat treatment and aging treatment on the forged alloy to obtain the alloy.

7. The method according to claim 6, wherein the ratio of the cross-sectional area before and after the first forging is 3 to 5: 1.

8. The method as claimed in claim 6, wherein the solution heat treatment temperature is 950-.

9. The method as claimed in claim 6, wherein the aging treatment temperature is 700-950 ℃, the holding time is 5-20h, and then the second cooling is performed.

10. The method of claim 8 or 9, wherein the cooling rate of the first cooling is more than or equal to 5 ℃/s; the cooling speed of the second cooling is more than or equal to 5 ℃/s.

Technical Field

The invention belongs to the field of alloy materials, and provides a low-density low-expansion high-entropy high-temperature alloy and a preparation method thereof.

Background

High temperature structural materials, represented by superalloys and intermetallic compounds, are key materials in the manufacture of hot end components of engines. With the rapid development of the fields of modern aerospace, energy, power and the like, more severe requirements are put forward on the literacy ability, the service performance, the specific gravity and the like of the high-temperature structural material. The nickel-based high-temperature alloy has higher room temperature and high temperature strength, excellent oxidation resistance, creep deformation and fatigue resistance and long-term structure stability, so that the nickel-based high-temperature alloy is a most widely applied high-temperature structural material in the hot end part of the current aerospace engine, wherein one of the deformation high-temperature alloys with the largest use amount is GH4169 at present. There are two main strengthening phases in GH4169 nickel-base superalloys: gamma prime and gamma "phases, but gamma" strengthening phases can only exist stably below 650 ℃. Therefore, GH4169 has relatively high strength at low and medium temperature stages. When the temperature is increased to above 650 ℃, the strengthening phase transformation becomes unstable, and the alloy strength is sharply reduced. Other relatively high strength alloys, such as GH4738, have higher strength than GH4169 at temperatures above 650℃, but have greater resistance to deformation, are difficult to process, and are not easily formed.

The cobalt-based high-temperature alloy has good thermal fatigue resistance, hot corrosion resistance and wear resistance at high temperature, and has higher thermal conductivity and lower thermal expansion performance compared with the nickel-based high-temperature alloy. The gamma 'phase in the cobalt-based high-temperature alloy is difficult to stably exist at high temperature, so that a gamma' phase precipitation strengthening mechanism cannot be realized, and the temperature bearing capacity of the cobalt-based high-temperature alloy is seriously limited. And the high-temperature mechanical property of the cobalt-based high-temperature alloy strengthened by the carbide is remarkably lower. In addition, cobaltThe cost of the base superalloy is too high, and the density even reaches 9g/cm³The above.

In order to further improve the thrust-weight ratio of the aerospace craft, weight reduction is a key technical means. The traditional nickel-based and cobalt-based high-temperature alloy is influenced by alloying elements, has higher density and is generally 8.2g/cm³Above, be unfavorable for improving the work efficiency of aircraft.

The high-entropy alloy is a novel alloy material which is paid attention in recent years and is different from the traditional alloy, consists of 5-13 main elements, and is mainly reflected in two aspects better than the traditional alloy: firstly, the composition design has high flexibility on the types and contents of alloy elements; and secondly, in terms of structure performance, after the multi-principal-element high-entropy alloy is solidified, a complex intermetallic compound is not formed, but a simple FCC or BCC solid solution is formed, so that the multi-principal-element high-entropy alloy has excellent mechanical properties, and also has special properties such as good catalytic performance, radiation resistance and the like. The high-entropy alloy has a thermodynamic high-entropy effect, a structural lattice distortion effect, a kinetic delayed diffusion effect and a performance cocktail effect. By utilizing the effects, the components of the alloy are reasonably designed, and the alloy has good comprehensive characteristics of high hardness, high strength, good wear resistance, corrosion resistance, high-temperature oxidation resistance and the like. Therefore, the high-entropy alloy has important scientific research value and wide application prospect due to flexible component design and excellent comprehensive performance.

At present, the research of the high-entropy alloy mainly focuses on the mechanical property at room temperature and even at low temperature, most of the high-entropy alloy is a single solid solution structure, and the solid solution strengthening effect is limited under the high-temperature condition. The currently developed refractory high-entropy alloy system has high-temperature strength, but poor plasticity and oxidation resistance, cannot be deformed due to low ductility at room temperature, and has high alloy density and high raw material cost. In conclusion, the existing high-entropy alloy can not fully meet the requirements of high-temperature oxidation resistance, creep resistance, fatigue resistance, long-term structure stability and good processability required by the materials of hot-end components of engines and gas turbines.

Disclosure of Invention

The application provides a low-density low-expansion high-entropy high-temperature alloy and a preparation method thereof, which aim to solve the technical problem of how to meet the requirements of low density and high temperature resistance of the high-entropy alloy.

The technical scheme for realizing the purpose is as follows:

a low-density low-expansion high-entropy high-temperature alloy comprises the following chemical components in percentage by mass: c: 0.02-0.10%, Cr: 20.5-25.0%, Co: 8.0-11.0%, Mo: 2.0-2.8%, Nb: 2.0-3.8%, W: 0.8-2.0%, Fe: 9.0-15.0%, Al: 1.0-4.0%, Ti: 2.5-6.0%, and the balance of Ni and inevitable impurity elements;

among the impurity elements, O is less than or equal to 0.005%, N is less than or equal to 0.005%, P is less than or equal to 0.015%, and S is less than or equal to 0.015%.

Optionally, the chemical composition of the alloy comprises, in mass fraction: : c: 0.02-0.08%, Cr: 20.5-23.0%, Co: 8.0-11.0%, Mo: 2.0-2.8%, Nb: 2.0-3.8%, W: 0.8-2.0%, Fe: 9.0-12.5%, A1: 1.0-3.0, Ti: 4.0-6.0 percent, and the balance of Ni and inevitable impurity elements.

Optionally, the sum of the mass fractions of Al and Ti is in a range of 6.5% to 9.5%.

Optionally, the density of the alloy is less than or equal to 8.0g/cm³(ii) a The alloy mainly comprises a gamma/gamma 'two-phase structure in volume fraction, wherein the gamma' phase volume fraction reaches 40-60%, and the balance is a gamma phase and a small amount of impurity phase.

Optionally, the alloy has a coefficient of thermal expansion of less than or equal to 15 x 10 at 800 DEG C^-6/K。

A method for preparing a low-density low-expansion high-entropy high-temperature alloy, which comprises the following steps:

obtaining a smelted alloy containing the chemical components;

performing first forging on the smelted alloy, and then remelting to obtain a remelted alloy;

performing secondary forging on the remelted alloy, wherein the temperature of the secondary forging is 950-1250 ℃, and then performing multiple forging forming to obtain a forged alloy;

and sequentially carrying out solid solution heat treatment and aging treatment on the forged alloy to obtain the alloy.

Optionally, the cross-sectional area ratio before and after the first forging is 3-5: 1.

Optionally, the temperature of the solution heat treatment is 950-.

Optionally, the temperature of the aging treatment is 700-.

Optionally, the cooling speed of the first cooling is more than or equal to 5 ℃/s; the cooling speed of the second cooling is more than or equal to 5 ℃/s.

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

the high-entropy high-temperature alloy provided by the embodiment of the invention has low density and low expansion, and has high-temperature strength, structural stability and good processability, C, Cr, Co, Ni, Mo, Nb, W, Fe, Al and Ti are accurately matched, multi-scale precipitation strengthening of micro-alloy elements is combined, transformation of phase change is inhibited, and a stable gamma/gamma' two-phase structure is obtained; by reasonably designing the components of alloy elements and adding low-density alloy elements such as Al, Ti and the like, the alloy disclosed by the invention has the advantages that the density is obviously reduced compared with that of the conventional high-temperature alloy, the high-temperature resistance is extremely high, and the cost of the alloy is comprehensively reduced. The high-entropy high-temperature alloy has the entropy of less than or equal to 8.0g/em³The low density of (2) can achieve good structure weight reduction effect in application.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a scanning electron microscope photograph of the high-entropy high-temperature alloy of the invention 1 after solution heat treatment;

FIG. 2 is a schematic flow chart of a method for preparing a low-density low-expansion high-entropy high-temperature alloy according to an embodiment of the present application.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.

Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

It should be further noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

In the present invention, "first forging", "second forging", "first cooling", and "second cooling" do not refer to a sequential relationship, and are used merely as terms for distinction.

In order to solve the technical problems, the technical scheme in the embodiment of the invention has the following general idea:

a low-density low-expansion high-entropy high-temperature alloy comprises the following chemical components in percentage by mass: c: 0.02-0.10%, Cr: 20.5-25.0%, Co: 8.0-11.0%, Mo: 2.0-2.8%, Nb: 2.0-3.8%, W: 0.8-2.0%, Fe: 9.0-15.0%, Al: 1.0-4.0%, Ti: 2.5-6.0%, and the balance of Ni and inevitable impurity elements; among the impurity elements, O is less than or equal to 0.005%, N is less than or equal to 0.005%, P is less than or equal to 0.015%, and S is less than or equal to 0.015%.

In the embodiment of the application, the alloy consists of 5 or more main elements (Ni, Cr, Co, Fe, Ti, Al, Nb and the like), so that an alloy system keeps a high entropy value and has a strong solid solution strengthening effect; meanwhile, the alloy microstructure is adjusted by adjusting the hot working process parameters and the heat treatment system, so that the strength of the alloy is further improved.

In the embodiment of the application, the high-entropy high-temperature alloy has the density of less than or equal to 8.0g/cm³The low density of the composite material can achieve good structure weight reduction effect in application; by adding 20.5-25.0% of Cr element and 1.0-4.0% of Al element, a compact oxide film is generated on the surface of the alloy, and the corrosion resistance of the alloy is obviously improved.

In the embodiment of the application, the components and the contents all meet the following requirements: the reason why O is less than or equal to 0.005, N is less than or equal to 0.005, P is less than or equal to 0.015 and S is less than or equal to 0.015 is that harmful elements such as N, O, P, S and the like are easy to generate inclusions with different forms with Al, Ti and the like in the alloy, are the initiation source and the expansion channel of fatigue cracks and reduce the performance of the alloy due to overlarge value.

As an alternative embodiment, the chemical composition of the alloy comprises, in mass fraction:

the chemical composition of the alloy comprises the following components in percentage by mass: : c: 0.02-0.08%, Cr: 20.5-23.0%, Co: 8.0-11.0%, Mo: 2.0-2.8%, Nb: 2.0-3.8%, W: 0.8-2.0%, Fe: 9.0-12.5%, Al: 1.0-3.0, Ti: 4.0-6.0 percent, and the balance of Ni and inevitable impurity elements.

As an alternative embodiment, the sum of the mass fractions of Al and Ti ranges from 6.5% to 9.5%.

By reasonably designing the components of alloy elements, adding low-density alloy elements such as Al, Ti and the like, and controlling the mass fraction of the Al, the Ti and the like to be more than or equal to 6.5% and less than or equal to 9.5 percent, the density of the alloy of the invention is obviously reduced compared with the prior high-temperature alloy, the cost of the alloy is reduced, in addition, the Al and the Ti enable the main elements forming the gamma 'phase, the A1 and the Ti are added and the content of the elements is controlled, the alloy has stable gamma' phase at the high temperature of 800 ℃, the volume fraction of the gamma 'phase is obviously improved to reach 40 to 60 percent, the lattice mismatching degree of the gamma-gamma' phase is improved, and the precipitation strengthening effect is obviously enhanced. The high-entropy high-temperature alloy has good processing performance. Compared with the existing refractory high-entropy alloy system, the alloy disclosed by the invention has the advantages of less surface cracks, good plasticity and high yield in the forging process. The sum of the mass fractions of Al and Ti in the alloy needs to be strictly controlled, and when the mass fraction is less than 6.5%, the density of the alloy is increased and exceeds 8.0g/cm³And the high-temperature strength is lower; when the mass fraction is more than 9.5 percent, harmful beta phase can be precipitated from the alloy, the structure is not stable, and the alloy plasticity is reduced, so the content of Al and Ti in the alloy is controlled to be more than or equal to 6.5 percent and less than or equal to 9.5 percent, the stable gamma/gamma' two-phase structure is ensured while the low density of the alloy is ensured, and the alloy has good hot workability.

As an alternative embodiment, the alloy has a density of not more than 8.0g/cm³(ii) a The alloy mainly comprises a gamma/gamma 'two-phase structure, wherein the gamma' phase accounts for 40-60% of the volume fraction, and the balance is a gamma phase and a small amount of impurity phase.

The alloy density of the embodiment of the invention is not more than 8.0g/cm³The high-temperature-resistant composite material is used for aerospace engine hot end components, can meet the use requirements of the components under the high-temperature service condition, achieves the effect of reducing the weight of the engine structure, and is an excellent high-temperature structure material. The alloy mainly comprises a gamma/gamma 'two-phase structure, a small amount of carbide and Laves which are equal, wherein the volume fraction of a gamma' phase reaches 40-60 percent, the balance is a gamma phase, and the content of impurity phases including carbide and other phases is less than or equal to 6 percent.

As an alternative embodiment, the alloy has a coefficient of thermal expansion of 15 x 10 ≦ at 800-⁶/K。

The high-entropy high-temperature alloy has lower thermal expansion coefficient at high temperatureNumber, coefficient of thermal expansion at 800 ℃ is less than or equal to 15 multiplied by 10^-6And the/K ensures that the internal stress generated by the machined parts in the service process is smaller, so that the service life of the parts in the high-temperature service environment is prolonged. And at 800 ℃, the alloy has a gamma ' phase and a gamma phase at the same time, and the volume fraction of the gamma ' phase reaches 40-60%, which shows that the alloy has a very stable microstructure, has higher heat resistance compared with the traditional alloy and the traditional low-temperature high-entropy alloy, and the proportion of the gamma ' phase and the gamma phase is basically unchanged at high temperature.

A method for preparing a low-density low-expansion high-entropy high-temperature alloy is shown in figure 2, and comprises the following steps:

s1, obtaining a smelted alloy containing the chemical components;

s2, performing first forging on the smelted alloy, and then remelting to obtain a remelted alloy;

s3, performing second forging on the remelted alloy, wherein the temperature of the second forging is 950-;

and S4, sequentially carrying out solid solution heat treatment and aging treatment on the forged alloy to obtain the alloy.

The reason why the first forging is performed as the electrode bar is to remelt the alloy ingot in order to improve the purity of the alloy and to improve the crystallization of the ingot.

In the embodiment of the application, the smelting is vacuum induction furnace smelting; the remelting is vacuum arc furnace remelting or vacuum electroslag remelting;

controlling the temperature of the second forging to be 950-1250 ℃, and forging and forming by multiple times of fire, wherein the forging specification is an alloy bar with the diameter of (20-100) mm.

The reason why the forging molding is performed a plurality of times is to obtain a uniform forged structure, and the reason why the solution heat treatment and the aging treatment are to control precipitation of a strengthening phase to obtain a microstructure having excellent properties.

As an alternative embodiment, the first forged electrode rod has a cross-sectional area ratio before and after forging of 3 to 5: 1. in the present embodiment, too low a forging ratio may result in residual as-cast structure, which may adversely affect the subsequent remelting step.

As an optional implementation mode, the heating temperature of the solution heat treatment is 950-.

In the embodiment of the application, the heating temperature of the solution heat treatment is controlled to be 950-.

As an optional implementation mode, the temperature of the aging treatment is 700-950 ℃, the heat preservation time is 5-20h, and then secondary cooling is carried out, so that higher room temperature and high temperature strength and better plasticity are obtained.

As an alternative embodiment, the cooling rate of the first cooling is more than or equal to 5 ℃/s; the cooling speed of the second cooling is more than or equal to 5 ℃/s.

Ultra-fast cooling is a fast cooling method; the whole cooling zone of laminar cooling is divided into a plurality of cooling sections, the cooling speed and the final cooling temperature of the plate strip steel are controlled by controlling the flow of water, starting the number of the cooling sections and changing the speed of a roller way, the laminar cooling is accelerated to control the cooling speed and the final cooling temperature more quickly and accurately, and any one of water cooling, fog cooling and air cooling can be adopted according to the shape of a target product and the difference of processing equipment.

The low-density low-expansion high-entropy high-temperature alloy provided by the embodiment of the invention and the production method thereof are explained in detail in the following by combining the embodiment and experimental data.

High-entropy high-temperature alloy of examples 1-6 of the invention and refractory Al of comparative example_0.4Hf_0.6The compositions of the NbTaTiZr (the high entropy alloy is marked by an atomic ratio and is 1 without the mark) high entropy alloy and the comparative GH4169 nickel-base superalloy are shown in tables 1 and 2.

The low-density low-expansion high-entropy high-temperature alloy comprises the following chemical components in percentage by mass: c: 0.02-0.10%, Cr: 20.5-25.0%, Co: 8.0-11.0%, Mo: 2.0-2.8%, Nb: 2.0-3.8%, W: 0.8-2.0%, Fe: 9.0-15.0%, Al: 1.0-4.0%, Ti: 2.5-6.0%, and the balance of Ni and inevitable impurity elements; among the impurity elements, O is less than or equal to 0.005%, N is less than or equal to 0.005%, P is less than or equal to 0.015%, and S is less than or equal to 0.015%. The scanning electron micrograph of example 1 is shown in FIG. 1.

In the embodiment, the high-entropy high-temperature alloy is prepared by smelting raw materials such as pure Cr, Co, Ni, Mo, Nb, W, Fe, Al, Ti, C and the like in a 50kg vacuum induction smelting furnace, refining at 1550 ℃ for 15min, and casting into an alloy ingot. And forging the alloy ingot into an electrode rod, and then carrying out vacuum electroslag remelting, wherein the current is controlled to be 2400-3400A. Forging the heavy-fusion gold ingot, wherein the forging heating temperature is 1050 +/-10 ℃, and forming by forging for multiple times, wherein the forging specification is phi 20mm alloy bar materials. Firstly carrying out solid solution heat treatment on the forged alloy bar, wherein the process comprises the steps of heating to 1050 ℃, preserving heat for 1 hour, and air cooling to obtain solid solution alloy; and then carrying out aging treatment, wherein the aging treatment process comprises the steps of keeping the temperature for 5 hours at 900 ℃, and carrying out air cooling to room temperature to obtain the low-density low-expansion high-entropy high-temperature alloy.

In each embodiment, the alloy is firstly smelted by a vacuum induction furnace and is subjected to electroslag remelting after being forged into an electrode rod.

And forging the remelted alloy into an alloy bar with the diameter of 20mm, carrying out solid solution and aging treatment through the heat treatment process, processing into a performance sample, and testing.

Table 1, chemistry (wt.%) of inventive examples 1-6 alloys and comparative alloys.

Alloy (I)	Cr	Co	Mo	Nb	W	Fe	C	Al	Ti	Ni
											Example 1	20.6	8.3	2.0	2.3	1.0	9.6	0.025	3.2	3.9	Surplus
Example 2	20.9	9.0	2.2	2.1	0.9	10.0	0.031	3.7	5.4	Surplus
											Example 3	21.7	9.6	2.3	2.9	1.4	13.1	0.027	3.8	2.7	Surplus
Example 4	23.1	10.2	2.5	3.2	1.4	12.3	0.060	1.6	5.0	Surplus
											Example 5	24.3	10.6	2.5	3.6	1.8	14.6	0.035	2.5	5.8	Surplus
Example 6	24.5	10.7	2.8	3.7	1.9	14.5	0.086	3.0	4.2	Surplus
											GH4169	18.8	0.1	3.1	5.2	-	Surplus	0.044	0.5	0.9	52.2

TABLE 2 comparative alloy A_10.4Hf_0.6Chemical composition (wt.%) of NbTaTiZr high entropy alloy.

In examples 1 to 6, the alloy impurity components and contents all satisfy the following requirements: o is less than or equal to 0.005, N is less than or equal to 0.005, P is less than or equal to 0.015, and S is less than or equal to 0.015.

Table 3 the densities and thermal expansion coefficients of the alloys of examples 1-6 of the present invention and the comparative alloys.

Alloys of examples 1-6 of the invention and comparative example Al_0.4Hf_0.6The thermal expansion coefficients of the NbTaTiZr high-entropy alloy and the comparative GH4169 alloy at 800 ℃ and 900 ℃ are shown in Table 3. As can be seen from Table 3, with Al_0.4Hf_0.6Compared with NbTaTiZr and GH4169, the thermal expansion coefficients of the alloys in examples 1-6 at 800 ℃ are significantly reduced, and are all lower than 15X 10^-6K; has a thermal expansion coefficient lower than 16 × 10 at 900 deg.C^-6/K。

Table 4 room temperature and high temperature mechanical properties of the alloys of examples 1-6 of the present invention and the comparative alloys.

The tensile properties at room temperature and at 800 ℃ for the alloys of examples 1-6 according to the invention and the comparative GH4169 alloy are shown in Table 4, in which Al is_0.4Hf_0.6The mechanical property of the NbTaTiZr high-entropy alloy is compressive strength. As can be seen by comparing the data, the high-entropy high-temperature alloy of the invention is compared with GH4169 and Al_0.4Hf_0.6The NbTaTiZr alloy can obviously improve the high-temperature yield strength, wherein the yield strength of the alloy in examples 2, 3 and 5 at the high temperature of 800 ℃ can reach more than 800MPa, and the yield strength of the alloy in examples 2, 4 and 5 at the high temperature of 900 ℃ can reach more than 700 MPa. The alloy is composed of 5 or more main elements, so that the alloy system keeps a higher entropy value and has strong solid solution strengthening effect; in addition, by adding Al and Ti elements and controlling the content of the Al and Ti elements, the alloy has a stable gamma' phase at a high temperature of more than 800 ℃, and plays a significant role in precipitation strengthening; meanwhile, the microstructure of the alloy is adjusted by adjusting the hot processing technological parameters and the heat treatment system, so that the strength of the alloy is further improved.

Fig. 1 is a photograph of the microstructure after the solution heat treatment in example 1, and it can be seen that a is a γ ' phase on the surface layer, b is a γ phase on the bottom layer, the entire microstructure is a γ '/γ two-phase structure, and the reinforcing phase γ ' phase accounts for 40-60% by volume fraction, and is very stable.

While preferred embodiments of the present invention have been described, 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.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.