High-specific-strength low-expansion high-entropy alloy and preparation method thereof

Abstract

The invention discloses a high-specific-strength low-expansion high-entropy alloy and a preparation method thereof, and belongs to the technical field of high-entropy alloys, the low-expansion high-entropy alloy is FeaNibCocCrdMeXf, M is one or more of Al, V and Ti, and X is one or more of C, N and Zr; a small amount of Al or Ti element is added into the alloy to reduce the density of the alloy, achieve the purpose of light weight and improve the strength of the alloy, and by adding V, C and N elements and introducing interstitial atoms, the stability of an alloy matrix FCC austenite phase is improved, generation of a BCC phase is inhibited, and the coefficient of thermal expansion is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material smelting and casting preparation, and particularly relates to a high specific strength and low expansion high-entropy alloy and a preparation method thereof. Background Art

[0002] For a long time, Invar Alloy has played an irreplaceable role in the fields of precision instruments, aerospace, and transportation due to its extremely low coefficient of thermal expansion (CTE). Its core advantage lies in being able to maintain dimensional stability within a wide temperature range, thus meeting the stringent requirements of high-precision equipment for thermal stability. However, due to the low strength, high density, and difficult forming of the Invar alloy material used in the existing precision system structures, the high-thermal-stability precision system structures face problems such as long manufacturing cycles, poor material matching, and insufficient weight reduction effects. The above problems seriously restrict the rapid development of this field. The design method of traditional alloys with one or two elements as the main elements severely limits the number of available alloy systems, making the development of traditional alloy systems tend to saturation and difficult to meet the various requirements of modern industry for the properties of metal materials. Therefore, it is urgent to break through the original traditional alloy system and develop new low-expansion and high-specific-strength alloy materials, which is the key way to realize the manufacturing of lightweight and high-thermal-stability precision system structures.

[0003] High-entropy alloys, with a brand-new multi-principal-element alloy design concept, break through the limitation of the composition space of traditional alloy design methods. High-entropy alloys adopt the design concept of multi-principal elements (usually ≥4 elements) with equal / near-equal molar ratios, and use several main elements with equal or near-equal concentrations as alloying elements. The synergistic effect between the main element atoms leads to a complex "cocktail" effect, which endows high-entropy alloys with diverse properties and microstructures, breaks through the limitations of traditional alloys, and has broad application prospects in structuring and functionalization. However, the existing research on high-entropy alloys mainly focuses on the optimization of mechanical properties, and the systematic research on the co-design of low thermal expansion coefficient and high specific strength is still blank. In addition, in some high-entropy alloy systems, it is easy to form body-centered cubic (BCC) phases or intermetallic compounds, resulting in an increase in the thermal expansion coefficient or deterioration of the processing performance, which limits their application in precision systems. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a high specific strength and low expansion high-entropy alloy and a preparation method thereof, so as to solve the problems in the prior art that Invar alloy has low strength and high density, and it is easy to form body-centered cubic phases or intermetallic compounds in high-entropy alloy systems.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A high specific strength and low expansion high-entropy alloy, wherein the low expansion high-entropy alloy is Fe aNi b Co c Cr d M e X f , wherein M is one or more of Al, V, and Ti, and X is one or more of C, N, and Zr; a, b, c, d, e, and f respectively represent the mass percentages of the corresponding elements, the range of a is 40 - 60%, the range of b is 10 - 35%, the range of c is 5 - 25%, the range of d is 1 - 10%, 0 < e + f ≤ 10%, 0 ≤ f ≤ 10% and a + b + c + d + e + f = 100%.

[0006] A further improvement of the present invention lies in: Preferably, for the low - expansion high - entropy alloy Fe a Ni b Co c Cr d M e X f , in terms of mass percentage, the range of a is 54 - 55%, the range of b is 20 - 30%, the range of c is 10 - 17%, the range of d is 2.7 - 3.7%, the range of e is 1 - 3%, and the range of f is 0 - 1.3%.

[0007] Preferably, when the low - expansion high - entropy alloy contains aluminum, the coefficient of thermal expansion is 4.9 - 7.0×10 -6 / K.

[0008] Preferably, when the low - expansion high - entropy alloy does not contain aluminum, the coefficient of thermal expansion is 2.5 - 3.7×10 -6 / K.

[0009] Preferably, for the low - expansion high - entropy alloy Fe a Ni b Co c Cr d M e X f , the Fe / Ni ratio is less than or equal to 3.

[0010] A preparation method of the above - mentioned high - specific - strength and low - expansion high - entropy alloy, comprising the following steps: Step 1, place the alloy in a furnace according to the set mass percentage for arc melting and casting to obtain an ingot; Step 2, perform solution heat treatment on the ingot to obtain the ingot after solution heat treatment; Step 3, perform cold rolling on the ingot after solution heat treatment; Step 4, perform recrystallization heat treatment on the rolled ingot, and air - cool it to room temperature after recrystallization heat treatment to obtain the high - specific - strength and low - expansion high - entropy alloy.

[0011] Preferably, in step 3, during the cold rolling process, the reduction in thickness is 0.5 - 1 mm.

[0012] Preferably, in step 3, during the cold rolling process, when the thickness is 1 - 2 mm away from the target thickness, the reduction in thickness per pass ≤ 0.3 mm.

[0013] Preferably, in step 2, the solution heat treatment temperature is 1000 °C and the holding time is 1 h.

[0014] Preferably, in step 4, the recrystallization heat treatment temperature is 1000 °C and the holding time is 3 min.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention designs a new type of high-entropy alloy with excellent performance. By adding a small amount of Al or Ti elements to the Fe a Ni b Co c Cr d matrix, the density of the alloy is reduced to achieve the purpose of lightweight, and the strength of the alloy is improved. By adding V, C, and N elements, interstitial atoms are introduced to improve the stability of the FCC austenite phase in the alloy matrix and inhibit the formation of the BCC phase, so as to achieve the purpose of reducing the thermal expansion coefficient.

[0016] According to the above formula, the present invention successfully obtains two groups of alloys, namely high-entropy Kovar containing Al and high-entropy Invar without Al, by using arc furnace melting, heat treatment and machining technologies, realizing the preparation of a new type of high-entropy alloy with low density, low thermal expansion coefficient and high strength.

[0017] Furthermore, by performing recrystallization treatment on the rolled samples for different times, the microstructure of the alloy is regulated, further reducing the thermal expansion coefficient of the high-entropy alloy and further strengthening and toughening the alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is an ingot sample of the Fe 54 Ni 30 Co 10 Cr3Al3 high-entropy alloy prepared by arc melting in Example 1 of the present invention.

[0019] Figure 2 This is a rolled sample of the Fe 54 Ni 30 Co 10 Cr3Al3 high-entropy alloy prepared by arc melting technology in Example 1 of the present invention after machining.

[0020] Figure 3 This is the Fe 54Ni 30 Co 10 EBSD images of the Cr3Al3 high-entropy alloy air-cooled after recrystallization at 1000 °C for 3 min.

[0021] Figure 4 Fe in the recrystallized state at 1000 °C / 3 min in Example 1 of the present invention 54 Ni 30 Co 10 Room-temperature tensile stress-strain curve of the Cr3Al3 high-entropy alloy.

[0022] Figure 5 Fe prepared by the arc melting technique in Example 1 of the present invention 54 Ni 30 Co 10 Coefficient of thermal expansion curve of the Cr3Al3 high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0023] Figure 6 Fe prepared by the arc melting technique in Example 2 of the present invention 54 Ni 23 Co 17 EBSD images of the Cr4Al2 high-entropy alloy air-cooled after recrystallization at 1000 °C for 3 min.

[0024] Figure 7 Fe prepared by the arc melting technique in Example 2 of the present invention 54 Ni 23 Co 17 Room-temperature tensile stress-strain curve of the Cr4Al2 high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0025] Figure 8 Fe prepared by the arc melting technique in Example 2 of the present invention 54 Ni 23 Co 17 Coefficient of thermal expansion curve of the Cr4Al2 high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0026] Figure 9 Fe prepared by the arc melting technique in Example 3 of the present invention 54 Ni 23 Co 17 Cr 2.7 Al2V1C 0.3 EBSD images of the high-entropy alloy after recrystallization at 1000 °C for 3 min.

[0027] Figure 10 Fe prepared by the arc melting technique in Example 3 of the present invention 54 Ni 23 Co17 Cr 2.7 Al2V1C 0.3 The room-temperature tensile stress-strain curve of the high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0028] Figure 11 For the Fe prepared by the arc melting technique in Example 3 of the present invention 54 Ni 23 Co 17 Cr 2.7 Al2V1C 0.3 The coefficient of thermal expansion curve of the high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0029] Figure 12 For the Fe prepared by the arc melting technique in Example 4 of the present invention 54 Ni 30 Co 10 Cr 2.7 Al2V1N 0.3 The EBSD images of the high-entropy alloy after recrystallization at 1000 °C for 3 min.

[0030] Figure 13 For the Fe prepared by the arc melting technique in Example 4 of the present invention 54 Ni 30 Co 10 Cr 2.7 Al2V1N 0.3 The room-temperature tensile stress-strain curve of the high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0031] Figure 14 For the Fe prepared by the arc melting technique in Example 4 of the present invention 54 Ni 30 Co 10 Cr 2.7 Al2V1N 0.3 The coefficient of thermal expansion curve of the high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0032] Figure 15 For the Fe prepared by the arc melting technique in Example 5 of the present invention 54 Ni 30 Co 10 Cr 2.7 Al2Ti1N 0.3 The EBSD images of the high-entropy alloy after recrystallization at 1000 °C for 3 min.

[0033] Figure 16 For the Fe prepared by the arc melting technique in Example 5 of the present invention 54 Ni 30 Co10 Cr 2.7 Al2Ti1N 0.3 The room temperature tensile stress-strain curve of the high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0034] Figure 17 For the Fe prepared by the arc melting technique in Example 5 of the present invention 54 Ni 30 Co 10 Cr 2.7 Al2Ti1N 0.3 The coefficient of thermal expansion curve of the high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0035] Figure 18 For the Fe prepared by the arc melting technique in Example 6 of the present invention 54 Ni 30 Co 10 Cr 2.5 Al2V1N 0.3 Zr 0.2 The EBSD images of the high-entropy alloy after recrystallization at 1000 °C for 3 min.

[0036] Figure 19 For the Fe prepared by the arc melting technique in Example 6 of the present invention 54 Ni 30 Co 10 Cr 2.5 Al2V1N 0.3 Zr 0.2 The room temperature tensile stress-strain curve of the high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0037] Figure 20 For the Fe prepared by the arc melting technique in Example 6 of the present invention 54 Ni 30 Co 10 Cr 2.5 Al2V1N 0.3 Zr 0.2 The coefficient of thermal expansion curve of the high-entropy alloy after recrystallization treatment at 1000 °C for 3 min.

[0038] Figure 21 For the Fe prepared by the arc melting technique in Example 7 of the present invention 55 Ni 23 Co 17 Cr 3.7 V1C 0.3 The EBSD images of the high-entropy alloy after recrystallization at 1000 °C for 3 min.

[0039] Figure 22For the Fe prepared by the arc melting technology in Example 7 of the present invention 55 Ni 23 Co 17 Cr 3.7 V1C 0.3 Room temperature tensile stress-strain curve of the high-entropy alloy after recrystallization treatment at 1000 °C / 3 min.

[0040] Figure 23 For the Fe prepared by the arc melting technology in Example 7 of the present invention 55 Ni 23 Co 17 Cr 3.7 V1C 0.3 Coefficient of thermal expansion curve of the high-entropy alloy after recrystallization treatment at 1000 °C / 3 min.

[0041] Figure 24 For the Fe prepared by the arc melting technology in Example 8 of the present invention 55 Ni 30 Co 10 Cr 3.7 V1N 0.3 EBSD images of the high-entropy alloy after recrystallization at 1000 °C / 3 min.

[0042] Figure 25 For the Fe prepared by the arc melting technology in Example 8 of the present invention 55 Ni 30 Co 10 Cr 3.7 V1N 0.3 Coefficient of thermal expansion curve of the high-entropy alloy after recrystallization treatment at 1000 °C / 3 min.

[0043] Figure 26 For the Fe prepared by the arc melting technology in Example 9 of the present invention 55 Ni 30 Co 10 Cr 3.7 Ti1N 0.3 EBSD images of the high-entropy alloy after recrystallization at 1000 °C / 3 min.

[0044] Figure 27 For the Fe prepared by the arc melting technology in Example 9 of the present invention 55 Ni 30 Co 10 Cr 3.7 Ti1N 0.3 Coefficient of thermal expansion curve of the high-entropy alloy after recrystallization treatment at 1000 °C / 3 min.

[0045] Figure 28 For the Fe prepared by the arc melting technology in Example 10 of the present invention55 Ni 30 Co 10 Cr 3.5 V1N 0.3 Zr 0.2 EBSD images of the high-entropy alloy after recrystallization at 1000 °C / 3 min.

[0046] Figure 29 For Example 10 of the present invention, Fe was prepared by arc melting technology 55 Ni 30 Co 10 Cr 3.5 V1N 0.3 Zr 0.2 Coefficient of thermal expansion curve of the high-entropy alloy after recrystallization treatment at 1000 °C / 3 min. Detailed implementation manners

[0047] The present invention will be further described in detail below with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art with respect to the present invention. In case of conflict, the definition in this specification shall prevail.

[0048] In this article, unless otherwise specified, "comprising", "including", "containing", "having" or similar expressions cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0049] The present invention will be further illustrated with specific examples below. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0050] Conventional instrument and equipment in the art are used in the following examples. For the experimental methods without specific conditions noted in the following examples, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following examples. Unless otherwise stated, commercially available products are used, and their specifications are the conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratios represent weight ratios.

[0051] The first aspect of the present invention discloses a high specific strength, low expansion high-entropy alloy, and the alloy components of the high-entropy alloy are Fe a Ni b Co c Cr d M e X f , where M is one or more of Al, V, and Ti, and X is one or more of C, N, and Zr; a, b, c, d, e, and f respectively represent the mass percentages of the corresponding elements. The range of a is 40-60%, the range of b is 10-35%, the range of c is 5-25%, the range of d is 1-10%, 0 < e + f ≤ 10%, 0 ≤ f ≤ 10%, and a + b + c + d + e + f = 100%.

[0052] Through the design of the above components, the present invention introduces interstitial atoms V, C, and N elements by adding V, C, and N elements. While improving the strength, it does not cause too much impact on the thermal expansion coefficient of the alloy, and improves the stability of the FCC austenite phase in the alloy matrix. On the one hand, V can form stable carbides and nitrides with C and N, thereby improving the strength of the alloy. On the other hand, C and N elements can improve the stability of austenite, help the alloy maintain a complete FCC phase, and inhibit the occurrence of martensitic shear and the formation of the BCC phase, so as to achieve the purpose of reducing the thermal expansion coefficient. In addition, Co and Cr elements in the alloy will also affect the thermal expansion coefficient of the alloy. The presence of a certain amount of Co element will increase the Curie temperature point of the alloy and can reduce the thermal expansion coefficient. However, the presence of a large amount of Co element will promote the formation of martensite, and then the alloy structure will transform into the BCC phase, resulting in an increase in the thermal expansion coefficient. Although the presence of Cr element will increase the thermal expansion coefficient of the alloy, it can hinder the occurrence of martensitic shear. And research shows that when there is a large amount of Co in the alloy, adding a small amount of Cr can effectively reduce the thermal expansion coefficient of the alloy.

[0053] In some embodiments of the present invention, the Fe / Ni ratio cannot be too large, and its ratio should be less than or equal to 3. Otherwise, the tissue stability will be reduced due to too high Fe content, and martensitic shear is very likely to occur during the cooling process, causing the tissue to transform into the BCC phase; In some embodiments of the present invention, in the Fe a Ni b Co c Cr d M e X f , by mass percentage, the range of a is 54-55%, the range of b is 20-30%, the range of c is 10-17%, the range of d is 2.7-3.7%, the range of e is 1-3%, and the range of f is 0-1.3%.

[0054] In some embodiments of the present invention, specific high-entropy alloys are disclosed, which are divided into two groups of alloys: high-entropy Kovar containing Al and high-entropy Invar without Al.

[0055] Exemplarily, the high-entropy Kovar alloy containing Al has a low coefficient of thermal expansion, and its coefficient of thermal expansion is basically distributed between 4.9 - 7.0×10 -6 / K, and the relevant components are Fe 54 Ni 30 Co 10 Cr3Al3, Fe 54 Ni 23 Co 17 Cr4Al2, Fe 54 Ni 23 Co 17 Cr 2.7 Al2V1C 0.3 , Fe 54 Ni 30 Co 10 Cr 2.7 Al2V1N 0.3 , Fe 54 Ni 30 Co 10 Cr 2.7 Al2Ti1N 0.3 , Fe 54 Ni 30 Co 10 Cr 2.5 Al2V1N 0.3 Zr 0.2 .

[0056] Exemplarily, the high-entropy Invar alloy without Al has an extremely low coefficient of thermal expansion, and its coefficient of thermal expansion is basically distributed in the range of 2.5 - 3.7×10 -6 / K, and the relevant components are Fe 55 Ni 23 Co 17 Cr 3.7 V1C 0.3 , Fe 55 Ni 30 Co 10 Cr 3.7 V1N 0.3 , Fe 55 Ni 30 Co 10 Cr 3.7 Ti1N 0.3 , Fe 55 Ni 30 Co 10 Cr 3.5 V1N0.3 Zr 0.2 。

[0057] In the above two component systems, an appropriate amount of Al element added in the present invention significantly optimizes the strength of the alloy, but also causes a slight increase in the coefficient of thermal expansion because the presence of Al element slightly increases the coefficient of thermal expansion of the alloy. Therefore, a system for removing Al element from the alloy is designed while ensuring the presence of Cr and Co. Adding a certain amount of Cr to the alloy containing a large amount of Co element can effectively reduce the coefficient of thermal expansion of the alloy.

[0058] The above high-entropy Invar alloys with different coefficients of thermal expansion can select the corresponding alloy according to the specific application scenario.

[0059] The second aspect of the present invention discloses a preparation method providing the above-mentioned arc melting and machining technologies of high specific strength and low expansion high-entropy alloy, including the following steps: Step 1, arc melting and casting of high-entropy alloy According to the designed mass percentage, melting is carried out in a vacuum arc furnace. Place the raw materials in the crucible of the arc furnace, evacuate to the reading of "composite unit" of the arc furnace reaching 3×10 -3 After closing the vacuum valve below, introduce argon gas to 0.05 MPa, repeat the evacuation process once for gas washing, reintroduce argon gas and then strike an arc to melt the Ti ingot in the center of the arc furnace for 3 min to absorb oxygen. After completing the deoxidation operation, melt the raw materials. The ingot needs to be turned over and melted 5 - 6 times to ensure the uniformity of the ingot composition. Then, pour the button-shaped ingot into the mold, wait for 10 min, take it out after complete cooling and solidification, and cut off the riser to obtain a high-entropy alloy strip ingot.

[0060] Step 2, in the present invention, to make the composition of the alloy uniform and to maintain the structure of single FCC austenite phase of the alloy, heat treatment is carried out on the Fe a Ni b Co c Cr d M e X f type high-entropy alloy. The process of the heat treatment is as follows: Heat the as-cast Fe a Ni b Co c Cr d M e X f type high-entropy alloy prepared by arc melting to 1000 °C for heat preservation, and the selected time is 1 h. After the heat preservation ends, air cooling is used to cool to room temperature. The cooling rate of air cooling is between furnace cooling and water quenching, which can effectively inhibit the formation of martensite and ferrite. Finally, the solution-treated high-entropy alloy is obtained.

[0061] Step 3, Machining of High-Entropy Alloys with Low Thermal Expansion Coefficient Measure the actual width and thickness of the high-entropy alloy bar-shaped ingot. At room temperature, perform cold rolling along the thickness direction of the sample. Initially, the reduction amount can be controlled at 0.5 - 1 mm. When there is still 1 - 2 mm left to the target thickness, the reduction amount per pass shall not be greater than 0.3 mm. The sample is rolled three times per pass to ensure uniform dimensions of each part of the sample. Repeat this process to roll the ingot to the target thickness and obtain the ingot.

[0062] Step 4, Recrystallization Heat Treatment Process After the above solution treatment of Fe a Ni b Co c Cr d M e X f type high-entropy alloy is subjected to cold rolling, and the rolled sample is subjected to recrystallization heat treatment for different times. Heat the rolled Fe a Ni b Co c Cr d M e X f type high-entropy alloy to 1000 °C and hold for a period of time. After holding for 3 min, air-cool to obtain the high-entropy alloy after recrystallization heat treatment. By subjecting the above arc-melted Fe a Ni b Co c Cr d M e X f high-entropy alloy to heat treatment, a lower cooling rate can effectively inhibit the occurrence of martensitic shear in the alloy. At the same time, a shorter recrystallization time can also retain some stress and defects in the alloy, making the Fe a Ni b Co c Cr d M e X f high-entropy alloy maintain a complete FCC phase, optimize the comprehensive mechanical properties of the alloy, and realize the preparation of low-expansion, high specific strength high-entropy alloys.

[0063] The following is further illustrated with specific examples.

[0064] Example 1 A low-expansion, high specific strength type high-entropy alloy manufactured by an arc melting technology. The chemical formula of the high-entropy alloy is Fe 54 Ni 30 Co 10 Cr3Al3; where the proportions of the elements are in mass percentages. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0065] In Example 1, an arc melting technology is used to prepare a high-entropy alloy. The forming process is as follows: Step 1: Melting and solution treatment of the high-entropy alloy ingot Weigh the metal raw materials corresponding to each element according to the mass ratio of each element in the nominal chemical composition of the high-entropy alloy above, with a total of 60 g. Use a vacuum arc furnace to melt them. Select metal particles with a purity of not less than 99.0%. Before starting the melting, evacuate the furnace until the reading of the "composite unit" of the arc furnace reaches 3×10 -3 After closing the vacuum valve, introduce argon gas to 0.05 MPa, repeat the evacuation process once for gas washing, reintroduce argon gas to 0.05 MPa and then strike an arc. Melt the Ti ingot in the center of the arc furnace for 3 minutes to absorb oxygen. After completing the deoxidation operation, melt the raw materials. The alloy ingot needs to be turned over and remelted 5-6 times, and then cast into a mold of 11.8×8 mm. Wait for 10 minutes. After the ingot has completely cooled and solidified, take it out. Its morphological state is as Figure 1 shown.

[0066] Step 2: After cutting off the riser, heat up to 1000 °C and hold for 1 hour. After the holding is completed, air cool to obtain a solution-treated sample.

[0067] Step 3: Machining of the ingot Cold roll the solution-treated sample along the 11.8 mm thick end. Adjust the distance between the rollers to a position slightly higher than 3-5 mm above the thickness of the ingot. Initially, the reduction can be controlled at 0.5-1 mm. When there is still 1-2 mm from the target thickness, the reduction per pass shall not be greater than 0.3 mm. Roll the sample three times per pass to ensure uniform dimensions of each part of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm. Its morphological state is as Figure 2 shown.

[0068] Step 4: Recrystallization treatment of the high-entropy alloy Heat up the cold-rolled sample to 1000 °C and hold for 3 minutes. After the holding is completed, air cool to obtain the high-entropy alloy after recrystallization treatment.

[0069] For the microstructure characterization and property testing of the high-entropy alloy, the electron backscatter diffraction analysis technology (EBSD) is used to observe the microstructure state and phase composition of the high-entropy alloy after recrystallization treatment. As Figure 3 shown, the alloy is basically completely recrystallized, and the microstructure is a complete FCC single phase. The heat treatment method plays a good role in suppressing the occurrence of martensitic shear in the alloy. After the recrystallization treatment in Example 1, Fe 54 Ni 30 Co 10The room-temperature yield strength of the Cr3Al3 high-entropy alloy is 269 MPa, the tensile strength is 547 MPa, and the elongation is 46.8%. The tensile strength is higher than that of traditional Invar alloys, as Figure 4 shown. After recrystallization treatment, the coefficient of thermal expansion of the Fe 54 Ni 30 Co 10 Cr3Al3 high-entropy alloy was measured. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion is 7.00×10 -6 / K, as Figure 5 shown.

[0070] Example 2 A low-expansion and high-specific-strength high-entropy alloy manufactured by an arc melting technique. The chemical formula of the high-entropy alloy is Fe 54 Ni 23 Co 17 Cr4Al2; where the proportion of each element is in mass percentage. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0071] Step 1, melting and solution treatment of the high-entropy alloy ingot According to the mass ratio of each element in the nominal chemical composition of the above high-entropy alloy, the raw materials are proportioned and melted using a vacuum arc furnace. The purity of the selected metal particles is greater than or equal to 99.0%. Before starting the melting, it is necessary to evacuate the vacuum until the reading of the "composite unit" of the arc furnace reaches 3×10 -3 After closing the vacuum valve below, argon gas is introduced to 0.05 MPa, and the vacuum evacuation process is repeated once for gas washing. After re-introducing argon gas to 0.05 MPa, an arc is struck, and the Ti ingot in the center of the melting arc furnace is melted for 3 minutes to absorb oxygen. After the deoxidation operation is completed, the raw materials are melted. The alloy ingot needs to be turned over and melted 5 - 6 times, and then cast into an 11.8×8 mm mold. Wait for 10 minutes, and take out the ingot after it has completely cooled and solidified.

[0072] Step 2, after cutting off the riser, heat up to 1000 °C and hold for 1 h. After the holding is completed, air-cool to obtain a solution-treated sample.

[0073] Step 3, machining of the ingot The solution-treated sample is cold-rolled along the 11.8 mm thick end. Adjust the distance between the rollers to a position slightly higher than 3 - 5 mm above the thickness of the ingot. Initially, the reduction can be controlled at 0.5 - 1 mm. When there is still 1 - 2 mm from the target thickness, the reduction per pass shall not be greater than 0.3 mm. The sample is rolled three times per pass to ensure uniform dimensions of each part of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0074] Step 4, recrystallization treatment of the high-entropy alloy The samples after cold rolling were heated to 1000 °C and held for 3 min, and then air-cooled after the holding to obtain the recrystallization-treated high-entropy alloy.

[0075] For the microstructure characterization and property testing of the high-entropy alloy, the electron backscatter diffraction analysis technique (EBSD) was used to observe the microstructure state and phase composition of the recrystallization-treated high-entropy alloy. As Figure 6 shown, the alloy was basically completely recrystallized, and the microstructure was a complete FCC single phase. The heat treatment method played a good role in suppressing the occurrence of martensitic shear in the alloy. After the recrystallization treatment in Example 2, Fe 54 Ni 23 Co 17 Cr4Al2 high-entropy alloy had a room-temperature yield strength of 247 MPa, a tensile strength of 509 MPa, and an elongation of 54.6%. The tensile strength was improved compared with that of the traditional Invar alloy. As Figure 7 shown. For the recrystallization-treated Fe 54 Ni 23 Co 17 Cr4Al2 high-entropy alloy, the coefficient of thermal expansion was measured. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion was 6.39×10 -6 / K. As Figure 8 shown.

[0076] Example 3 A low-expansion and high-specific-strength high-entropy alloy manufactured by an arc melting technique. The chemical formula of the high-entropy alloy is Fe 54 Ni 23 Co 17 Cr 2.7 Al2V1C 0.3 ; where the proportions of the elements are in mass percentages. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0077] Step 1, melting and solution treatment of the high-entropy alloy ingot. According to the mass ratio of each element in the nominal chemical composition of the above high-entropy alloy, the ingredients were proportioned and melted using a vacuum arc furnace. The purity of the selected metal particles was greater than or equal to 99.0%. Before starting the melting, it was necessary to evacuate to the reading of the "composite unit" of the arc furnace reaching 3×10 -3 or below. After closing the vacuum valve, argon was introduced to 0.05 MPa, and the vacuum evacuation process was repeated once for gas washing. After re-introducing argon to 0.05 MPa, the arc was initiated, and the Ti ingot in the center of the melting arc furnace was melted for 3 min to absorb oxygen. After the deoxidation operation was completed, the raw materials were melted. The alloy ingot needed to be turned over and melted 5 - 6 times, and then cast into an 11.8×8 mm mold. After waiting for 10 min, the ingot was taken out after complete cooling and solidification.

[0078] Step 2: After cutting off the riser, heat it up to 1000 °C and hold for 1 h. After the holding is completed, air-cool it to obtain a solution-treated sample.

[0079] Step 3: Machining of the ingot Cold-roll the solution-treated sample along the 11.8-mm thick end. Adjust the distance between the rollers to a position slightly higher than 3 - 5 mm above the thickness of the ingot. Initially, the reduction can be controlled at 0.5 - 1 mm. When there is still 1 - 2 mm to the target thickness, the reduction per pass shall not be greater than 0.3 mm. Roll the sample three times per pass to ensure uniform dimensions of each part of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0080] Step 4: Recrystallization treatment of the high-entropy alloy Heat up the cold-rolled sample to 1000 °C and hold for 3 min. After the holding is completed, air-cool it to obtain the high-entropy alloy after recrystallization treatment.

[0081] Characterize the microstructure and test the properties of the high-entropy alloy. Use electron backscatter diffraction analysis technology (EBSD) to observe the microstructure state and phase composition of the high-entropy alloy after recrystallization treatment, as Figure 9 shown. The alloy is basically completely recrystallized, and the microstructure is a complete FCC single phase. The heat treatment method has played a good role in suppressing the occurrence of martensitic shear in the alloy. After the recrystallization treatment in Example 3, Fe 54 Ni 23 Co 17 Cr 2.7 Al2V1C 0.3 The room-temperature yield strength of the high-entropy alloy is 490 MPa, the tensile strength is 737 MPa, and the elongation is 33.8%. The yield and tensile strengths are significantly improved compared with traditional Invar alloys, as Figure 10 shown. Measure the coefficient of thermal expansion of the Fe 54 Ni 23 Co 17 Cr 2.7 Al2V1C 0.3 high-entropy alloy after recrystallization treatment. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion is 4.98×10 -6 / K, as Figure 11 shown.

[0082] Example 4 A low-expansion and high-specific-strength high-entropy alloy manufactured by an arc melting technique. The chemical formula of the high-entropy alloy is Fe 54 Ni 30 Co 10 Cr 2.7 Al2V1N 0.3; among them, the proportion of each element is in mass percentage. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0083] Step 1, melting and solution treatment of the high-entropy alloy ingot Mix according to the mass ratio of each element in the nominal chemical composition of the above high-entropy alloy, and use a vacuum arc furnace to melt it. The purity of the selected metal particles is greater than or equal to 99.0%. Before starting the melting, evacuate to the reading of the "composite unit" of the arc furnace reaching 3×10 -3 After closing the vacuum valve below, pass argon to 0.05 MPa, repeat the evacuation process once for gas washing, and after re-passing argon to 0.05 MPa, strike an arc, melt the Ti ingot in the center of the arc furnace for 3 minutes to absorb oxygen. After completing the deoxidation operation, melt the raw materials. The alloy ingot needs to be turned over and cast 5-6 times, and then cast into a mold of 11.8×8 mm, wait for 10 minutes, and take out the ingot after it has cooled and solidified completely.

[0084] Step 2, heat up to 1000 °C after cutting off the riser and hold for 1 hour. The selected time is 1 hour. After the holding is over, air cool to obtain a solution-treated sample.

[0085] Step 3, machining of the ingot Cold roll the solution-treated sample along the 11.8 mm thick end, adjust the distance between the rolls to a position slightly higher than 3-5 mm of the ingot thickness. Initially, the reduction can be controlled at 0.5-1 mm. When there is still 1-2 mm from the target thickness, the reduction per pass shall not be greater than 0.3 mm. The sample is rolled three times per pass to ensure uniform dimensions of each part of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0086] Step 4, recrystallization treatment of the high-entropy alloy Heat up the cold-rolled sample to 1000 °C and hold for 3 minutes. The selected time is 3 minutes. After the holding is over, air cool to obtain the high-entropy alloy after recrystallization treatment.

[0087] For the microstructure characterization and property testing of the high-entropy alloy, use the electron backscatter diffraction analysis technique (EBSD) to observe the microstructure state and phase composition of the high-entropy alloy after recrystallization treatment, as Figure 12 shown, the alloy is basically completely recrystallized, and the structure is a complete FCC single phase. The heat treatment method has played a good role in suppressing the occurrence of martensitic shear in the alloy. After the recrystallization treatment in Example 4, Fe 54 Ni 30 Co 10 Cr 2.7 Al2V1N 0.3 The room temperature yield strength of the high-entropy alloy is 237 MPa, the tensile strength is 524 MPa, and the elongation is 52.3%. The tensile strength is higher than that of the traditional invar alloy, as Figure 13As shown, for the recrystallized Fe 54 Ni 30 Co 10 Cr 2.7 Al2V1N 0.3 high-entropy alloy, the coefficient of thermal expansion was measured. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion was 5.91×10 -6 / K, as Figure 14 shown.

[0088] Example 5 A low-expansion and high-specific-strength high-entropy alloy manufactured by an arc melting technique. The chemical formula of the high-entropy alloy is Fe 54 Ni 30 Co 10 Cr 2.7 Al2Ti1N 0.3 ; where the proportions of the elements are in mass percentages. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0089] Step 1, melting and solution treatment of the high-entropy alloy ingot Weigh the elements according to the mass ratio in the nominal chemical composition of the above high-entropy alloy and use a vacuum arc furnace to melt it. The purity of the selected metal particles is greater than or equal to 99.0%. Before starting the melting, evacuate to the "composite unit" reading of the arc furnace reaching 3×10 -3 below, then close the vacuum valve and fill with argon to 0.05 MPa. Repeat the evacuation process once for gas washing. After refilling with argon to 0.05 MPa, strike an arc and melt the Ti ingot in the center of the arc furnace for 3 minutes to absorb oxygen. After completing the deoxidation operation, melt the raw materials. The alloy ingot needs to be turned over and melted 5 - 6 times, and then cast into an 11.8×8 mm mold. Wait for 10 minutes and take out the ingot after it has completely cooled and solidified.

[0090] Step 2, cut off the riser and heat up to 1000 °C for insulation for 1 hour. After the insulation is completed, air cool to obtain a solution-treated sample.

[0091] Step 3, machining of the ingot Cold roll the solution-treated sample along the 11.8 mm thick end. Adjust the distance between the rollers to a position slightly higher than 3 - 5 mm above the ingot thickness. Initially, the reduction can be controlled at 0.5 - 1 mm. When there is still 1 - 2 mm from the target thickness, the reduction per pass shall not be greater than 0.3 mm. Roll the sample three times per pass to ensure uniform dimensions of all parts of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0092] Step 4, recrystallization treatment of the high-entropy alloy The cold-rolled sample was heated to 1000 °C and held for 3 minutes, and then air-cooled after heat preservation to obtain a recrystallized high-entropy alloy.

[0093] For the microstructure characterization and property testing of the high-entropy alloy, the electron backscatter diffraction analysis technique (EBSD) was used to observe the microstructure state and phase composition of the recrystallized high-entropy alloy, as Figure 15 shown. The alloy was basically completely recrystallized, and the microstructure was a complete FCC single phase. The heat treatment method played a good role in suppressing the occurrence of martensitic shear in the alloy. After the recrystallization treatment in Example 5, Fe 54 Ni 30 Co 10 Cr 2.7 Al2Ti1N 0.3 The room-temperature yield strength of the high-entropy alloy was 264 MPa, the tensile strength was 551 MPa, the tensile strength was higher than that of the traditional invar alloy, and the elongation was 47.6%, as Figure 16 shown. For the Fe 54 Ni 30 Co 10 Cr 2.7 Al2Ti1N 0.3 The coefficient of thermal expansion of the high-entropy alloy was measured. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion was 6.21×10 -6 / K, as Figure 17 shown.

[0094] Example 6 A low-expansion and high-specific-strength high-entropy alloy manufactured by an arc melting technique, and the chemical formula of the high-entropy alloy is Fe 54 Ni 30 Co 10 Cr 2.5 Al2V1N 0.3 Zr 0.2 ; where the proportions of the elements are in mass percentages. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0095] Step 1, melting and solution treatment of the high-entropy alloy ingot According to the mass ratio of each element in the nominal chemical composition of the above high-entropy alloy, the mixture was proportioned and melted using a vacuum arc furnace. The purity of the selected metal particles was greater than or equal to 99.0%. Before starting the melting, it was necessary to evacuate to the reading of the "composite unit" of the arc furnace reaching 3×10 -3After closing the vacuum valve as follows, argon gas is introduced to 0.05 MPa, and the vacuum pumping process is repeated once for gas washing. After introducing argon gas to 0.05 MPa again, arc striking is carried out, and the Ti ingot in the center of the melting electric arc furnace is melted for 3 minutes to absorb oxygen. After completing the deoxidation operation, the raw materials are melted. The alloy ingot needs to be turned over and melted 5 - 6 times, and then cast into a 11.8×8 mm mold. Wait for 10 minutes, and take out the ingot after it is completely cooled and solidified.

[0096] Step 2: After removing the riser, heat up to 1000 °C and hold for 1 hour. After the holding is completed, air cooling is carried out to obtain a solution-treated sample.

[0097] Step 3: Machining of the ingot The solution-treated sample is cold-rolled along the 11.8 mm thick end. Adjust the distance between the rollers to a position slightly higher than 3 - 5 mm of the ingot thickness. Initially, the reduction can be controlled at 0.5 - 1 mm. When there is still 1 - 2 mm from the target thickness, the reduction per pass shall not be greater than 0.3 mm. The sample is rolled three times per pass to ensure uniform dimensions of each part of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0098] Step 4: Recrystallization treatment of the high-entropy alloy The cold-rolled sample is heated to 1000 °C and held for 3 minutes. After the holding is completed, air cooling is carried out to obtain the high-entropy alloy after recrystallization treatment.

[0099] For the microstructure characterization and property testing of the high-entropy alloy, the electron backscatter diffraction analysis technique (EBSD) is used to observe the microstructure state and phase composition of the high-entropy alloy after recrystallization treatment, as Figure 18 shown. The alloy is basically completely recrystallized, and the microstructure is a complete FCC single phase. The heat treatment method has played a good role in suppressing the occurrence of martensitic shear in the alloy. After recrystallization treatment in Example 6, Fe 54 Ni 30 Co 10 Cr 2.5 Al2V1N 0.3 Zr 0.2 The room temperature yield strength of the high-entropy alloy is 302 MPa, the tensile strength is 494 MPa, and the elongation is 19.4%. The yield strength is improved compared with the traditional invar alloy, as Figure 19 shown. For the Fe 54 Ni 30 Co 10 Cr 2.5 Al2V1N 0.3 Zr 0.2 The high-entropy alloy is measured for the coefficient of thermal expansion. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion is 6.18×10 -6 / K, as Figure 20as shown

[0100] Example 7 A low-expansion, high specific strength high-entropy alloy manufactured by an arc melting technique, and the chemical formula of the high-entropy alloy is Fe 55 Ni 23 Co 17 Cr 3.7 V1C 0.3 ; wherein, the proportion of each element is in mass percentage. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0101] Step 1, melting and solution treatment of the high-entropy alloy ingot Mix according to the mass ratio of each element in the nominal chemical composition of the above high-entropy alloy, and use a vacuum arc furnace to melt it. The purity of the selected metal particles is greater than or equal to 99.0%. Before starting the melting, evacuate to the reading of the "composite unit" of the arc furnace reaching 3×10 -3 After closing the vacuum valve below, pass argon gas to 0.05 MPa, repeat the evacuation process once for gas washing, and after re-passing argon gas to 0.05 MPa, strike an arc, melt the Ti ingot in the center of the melting arc furnace for 3 minutes to absorb oxygen. After completing the deoxidation operation, melt the raw materials. The alloy ingot needs to be turned over and cast 5-6 times, and then cast into a 11.8×8 mm mold. Wait for 10 minutes, and take out the ingot after it has completely cooled and solidified.

[0102] Step 2, after cutting off the riser, heat up to 1000 °C and hold for 1 hour, and then air cool after the holding is over to obtain a solution-treated sample.

[0103] Step 3, machining of the ingot Cold roll the solution-treated sample along the 11.8 mm thick end, adjust the distance between the rollers to a position slightly higher than 3-5 mm of the ingot thickness. Initially, the reduction can be controlled at 0.5-1 mm. When there is still 1-2 mm from the target thickness, the reduction per pass shall not be greater than 0.3 mm. The sample is rolled three times per pass to ensure uniform dimensions of each part of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0104] Step 4, recrystallization treatment of the high-entropy alloy Heat up the cold-rolled sample to 1000 °C and hold for 3 minutes, and then air cool after the holding is over to obtain the high-entropy alloy after recrystallization treatment.

[0105] For the microstructure characterization and property testing of the high-entropy alloy, use the electron backscatter diffraction analysis technique (EBSD) to observe the microstructure state and phase composition of the high-entropy alloy after recrystallization treatment, such as Figure 21As shown, the alloy is basically fully recrystallized, and the microstructure is a complete FCC single phase. The heat treatment method has a good inhibitory effect on the occurrence of martensitic shear in the alloy. After the recrystallization treatment in Example 7, Fe 55 Ni 23 Co 17 Cr 3.7 V1C 0.3 The room temperature yield strength of the high-entropy alloy is 429 MPa, the tensile strength is 698 MPa, and the elongation is 44.9%. The yield and tensile strengths are significantly improved compared with traditional Invar alloys, as Figure 22 shown. After the recrystallization treatment of Fe 55 Ni 23 Co 17 Cr 3.7 V1C 0.3 the high-entropy alloy was measured for the coefficient of thermal expansion. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion is 2.78×10 -6 / K, as Figure 23 shown.

[0106] Example 8 A low-expansion and high-specific-strength high-entropy alloy manufactured by an arc melting technique, and the chemical formula of the high-entropy alloy is Fe 55 Ni 30 Co 10 Cr 3.7 V1N 0.3 ; wherein, the proportions of the elements are in mass percentages. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0107] Step 1, melting and solution treatment of the high-entropy alloy ingot According to the mass ratio of each element in the nominal chemical composition of the high-entropy alloy above, proportioning is carried out, and it is melted using a vacuum arc furnace. The purity of the selected metal particles is greater than or equal to 99.0%. Before starting the melting, it is necessary to evacuate to the reading of the "composite unit" of the arc furnace reaching 3×10 -3 below. After closing the vacuum valve, argon is introduced to 0.05 MPa, and the vacuum pumping process is repeated once for gas washing. After re-introducing argon to 0.05 MPa, an arc is struck, and the Ti ingot in the center of the melting arc furnace is melted for 3 min to absorb oxygen. After completing the deoxidation operation, the raw materials are melted. The alloy ingot needs to be turned over and melted 5 - 6 times, and then cast into an 11.8×8 mm mold. Wait for 10 min, and take out the ingot after it has cooled and solidified completely.

[0108] Step 2, after cutting off the riser, heat up to 1000 °C and hold for 1 h. After the holding is completed, air-cool to obtain a solution-treated sample.

[0109] Step 3, machining of the ingot The solution-treated sample is cold-rolled along the 11.8 mm thick end. Adjust the distance between the rollers to a position slightly higher than 3 - 5 mm above the ingot thickness. Initially, the reduction can be controlled at 0.5 - 1 mm. When there is still 1 - 2 mm to the target thickness, the reduction per pass shall not be greater than 0.3 mm. The sample is rolled three times per pass to ensure uniform dimensions of all parts of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0110] Step 4, Recrystallization treatment of the high-entropy alloy The cold-rolled sample is heated to 1000 °C and held for 3 minutes. After holding, it is air-cooled to obtain the recrystallization-treated high-entropy alloy.

[0111] For the microstructure characterization and property testing of the high-entropy alloy, the electron backscatter diffraction analysis technique (EBSD) is used to observe the microstructure state and phase composition of the recrystallization-treated high-entropy alloy, as Figure 24 shown. The alloy is basically completely recrystallized, and the microstructure is a complete FCC single phase. The heat treatment method has played a good role in suppressing the occurrence of martensitic shear in the alloy. For the recrystallization-treated Fe 55 Ni 30 Co 10 Cr 3.7 V1N 0.3 high-entropy alloy, the coefficient of thermal expansion is measured. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion is 3.65×10 -6 / K, as Figure 25 shown.

[0112] Example 9 A low-expansion and high-specific-strength high-entropy alloy manufactured by an arc melting technique. The chemical formula of the high-entropy alloy is Fe 55 Ni 30 Co 10 Cr 3.7 Ti1N 0.3 ; where the proportions of the elements are in mass percentages. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0113] Step 1, Ingot melting and solution treatment of the high-entropy alloy According to the mass ratio of each element in the nominal chemical composition of the above high-entropy alloy, the materials are proportioned and melted using a vacuum arc furnace. The purity of the selected metal particles is greater than or equal to 99.0%. Before starting the melting, it is necessary to evacuate to the reading of the "composite unit" of the arc furnace reaching 3×10 -3After closing the vacuum valve below, argon is passed through until it reaches 0.05 MPa, and the vacuum pumping process is repeated once for gas washing. After argon is re-introduced to 0.05 MPa, an arc is initiated, and the Ti ingot in the center of the melting electric arc furnace is melted for 3 minutes to absorb oxygen. After the deoxidation operation is completed, the raw materials are melted. The alloy ingot needs to be turned over and melted 5 - 6 times, and then cast into a mold of 11.8×8 mm. Wait for 10 minutes, and take out the ingot after it has completely cooled and solidified.

[0114] Step 2, After cutting off the riser, heat up to 1000 °C and hold for 1 hour. After the holding is completed, air-cool to obtain a solution-treated sample.

[0115] Step 3, Machining of the ingot The solution-treated sample is cold-rolled along the 11.8 mm thick end. Adjust the distance between the rollers to a position slightly higher than 3 - 5 mm above the thickness of the ingot. Initially, the reduction can be controlled at 0.5 - 1 mm. When there is still 1 - 2 mm from the target thickness, the reduction per pass shall not be greater than 0.3 mm. The sample is rolled three times per pass to ensure uniform dimensions of all parts of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0116] Step 4, Recrystallization treatment of the high-entropy alloy The cold-rolled sample is heated to 1000 °C and held for 3 minutes. After the holding is completed, air-cool to obtain the high-entropy alloy after recrystallization treatment.

[0117] For the microstructure characterization and property testing of the high-entropy alloy, the electron backscatter diffraction analysis technique (EBSD) is used to observe the microstructure state and phase composition of the high-entropy alloy after recrystallization treatment, as Figure 26 shown. The alloy is basically completely recrystallized, and the microstructure is a complete FCC single phase. The heat treatment method has played a good role in suppressing the occurrence of martensitic shear in the alloy. For the Fe 55 Ni 30 Co 10 Cr 3.7 Ti1N 0.3 The high-entropy alloy is measured for the coefficient of thermal expansion. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion is 3.69×10 -6 / K, as Figure 27 shown.

[0118] Example 10 A low-expansion and high-specific-strength high-entropy alloy manufactured by an arc melting technology. The chemical formula of the high-entropy alloy is Fe 55 Ni 30 Co 10 Cr 3.5 V1N 0.3 Zr 0.2; among them, the proportions of the elements are in mass percentages. The purity of the selected metal raw materials is greater than or equal to 99.0%.

[0119] Step 1, melting and solution treatment of the high-entropy alloy ingot Mix according to the mass ratio of each element in the nominal chemical composition of the high-entropy alloy above, and use a vacuum arc furnace to melt it. The purity of the selected metal particles is greater than or equal to 99.0%. Before starting the melting, evacuate to the reading of the "composite unit" of the arc furnace reaching 3×10 -3 After closing the vacuum valve below, pass argon gas to 0.05 MPa, repeat the evacuation process once for gas washing, re-pass argon gas to 0.05 MPa and then strike an arc, melt the Ti ingot in the center of the arc furnace for 3 minutes to absorb oxygen. After completing the deoxidation operation, melt the raw materials. The alloy ingot needs to be turned over and cast 5 - 6 times, and then cast into a 11.8×8 mm mold. Wait for 10 minutes, and take out the ingot after it has completely cooled and solidified.

[0120] Step 2, after cutting off the riser, heat up to 1000 °C and hold for 1 hour. After the holding is completed, air cool to obtain a solution-treated sample.

[0121] Step 3, machining of the ingot Cold roll the solution-treated sample along the 11.8 mm thick end. Adjust the distance between the rollers to a position slightly higher than 3 - 5 mm of the ingot thickness. Initially, the reduction can be controlled at 0.5 - 1 mm. When there is still 1 - 2 mm from the target thickness, the reduction per pass shall not be greater than 0.3 mm. The sample is rolled three times per pass to ensure uniform dimensions of each part of the sample. Repeat this process to roll the ingot to a thickness of 5.9 mm.

[0122] Step 4, recrystallization treatment of the high-entropy alloy Heat up the cold-rolled sample to 1000 °C and hold for 3 minutes. After the holding is completed, air cool to obtain the high-entropy alloy after recrystallization treatment.

[0123] For the microstructure characterization and property testing of the high-entropy alloy, use the electron backscatter diffraction analysis technique (EBSD) to observe the microstructure state and phase composition of the high-entropy alloy after recrystallization treatment, as Figure 28 shown. The alloy is basically completely recrystallized, and the microstructure is a complete FCC single phase. The heat treatment method has played a good role in suppressing the occurrence of martensitic shear in the alloy. For the Fe 55 Ni 30 Co 10 Cr 3.5 V1N 0.3 Zr 0.2 Measure the coefficient of thermal expansion of the high-entropy alloy. In the temperature range of 30 - 150 °C, the average coefficient of thermal expansion is 3.41×10 -6 / K, asFigure 29 as shown

[0124] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-entropy alloy with high specific strength and low expansion, characterized in that, The low-expansion high-entropy alloy is Fe a Ni b Co c Cr d M e X f , where M is one or more of Al, V, and Ti, and X is one or more of C, N, and Zr; a, b, c, d, e, and f respectively represent the mass percentages of the corresponding elements, the range of a is 40-60%, the range of b is 10-35%, the range of c is 5-25%, the range of d is 1-10%, 0 < e + f ≤ 10%, 0 ≤ f ≤ 10%, and a + b + c + d + e + f = 100%.

2. The high-entropy alloy with high specific strength and low expansion according to claim 1, wherein Low-expansion high-entropy alloy Fe a Ni b Co c Cr d M e X f wherein, by mass percentage, the range of a is 54 - 55%, the range of b is 20 - 30%, the range of c is 10 - 17%, the range of d is 2.7 - 3.7%, the range of e is 1 - 3%, and the range of f is 0 - 1.3%.

3. The high-entropy alloy with high specific strength and low expansion according to claim 1, characterized in that, When the low-expansion high-entropy alloy contains aluminum, the coefficient of thermal expansion is 4.9 - 7.0×10 -6 / K.

4. A high-entropy alloy with high specific strength and low expansion according to claim 1, characterized in that When aluminum is not contained in the low-expansion high-entropy alloy, the coefficient of thermal expansion is 2.5 - 3.7×10 -6 / K.

5. A high-entropy alloy with high specific strength and low expansion according to claim 1, characterized in that, Low-expansion high-entropy alloy Fe a Ni b Co c Cr d M e X f In this case, the Fe / Ni ratio is less than or equal to 3.

6. A method for preparing a high-entropy alloy with high specific strength and low expansion as claimed in claim 1, characterized in that, It includes the following steps: Step 1: Place the alloy in a furnace for arc melting and casting according to the set mass percentage to obtain an ingot; Step 2: Perform solution heat treatment on the ingot to obtain the ingot after solution heat treatment; Step 3: Perform cold rolling on the ingot after solution heat treatment; Step 4: Perform recrystallization heat treatment on the rolled ingot, air cool it to room temperature after recrystallization heat treatment to obtain a high-entropy alloy with high specific strength and low expansion.

7. The preparation method according to claim 6, wherein In Step 3, during the cold rolling process, the reduction in thickness is 0.5 - 1 mm.

8. The preparation method according to claim 6, characterized in that, In Step 3, during the cold rolling process, when there is still 1 - 2 mm to the target thickness, the reduction in thickness per pass ≤ 0.3 mm.

9. The preparation method according to claim 6, characterized in that, In Step 2, the solution heat treatment temperature is 1000 °C and the holding time is 1 h.

10. The preparation method according to claim 6, characterized in that, In Step 4, the recrystallization heat treatment temperature is 1000 °C and the holding time is 3 min.

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