A low-expansion constant-modulus alloy and a method for producing the same

Abstract

The application belongs to the technical field of materials, and discloses a low-expansion constant modulus alloy and a preparation method thereof. 54‑2x Ni 23‑2x Co 17 Cr 6+x Cu 3x , 0≤x≤2, the method comprises the following steps: taking Fe, Ni, Co, Cr and Cu according to the chemical formula respectively by weight percentage, mixing uniformly to obtain a first material; repeatedly melting the first material in an electric arc furnace for at least 5 times to obtain an alloy ingot; hot rolling the alloy ingot into a plate to obtain a low-expansion constant modulus alloy. The method changes the microstructure of the alloy by doping elements, realizes a controllable low-expansion coefficient, and the alloy has the characteristics of constant modulus. A series of alloys with low-expansion performance and constant modulus can be prepared by the method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of materials, and particularly relates to a low-expansion constant modulus alloy and a preparation method thereof. BACKGROUND

[0002] Low-expansion alloy refers to a kind of alloy material that exhibits a low expansion coefficient in a specific temperature range. In nature, most solid materials will change in volume or length with temperature fluctuations, i.e. thermal expansion and contraction, and their elastic modulus often increases with decreasing temperature. For precision instruments operating in extreme environmental conditions, dimensional changes of internal components and temperature dependence of elastic modulus can cause serious thermal mechanical stress, thereby causing system performance degradation or even catastrophic failure. Guillaume first observed a unique physical phenomenon, i.e. low expansion characteristics (Invar effect), in Fe-36Ni alloy, which almost does not change in size with temperature change in a wide temperature range, exhibiting extremely low thermal expansion coefficient. At the same time, he also found that the elastic modulus of the alloy remains constant in a wide temperature range (Elinvar effect). These characteristics make Fe-Ni-based low-expansion alloy an indispensable material in high-tech fields such as instrument components, electronic device packaging, precision measurement equipment, liquefied natural gas (LNG) transport ships, special transmission cables, and aerospace, with great market demand and application potential.

[0003] Regarding the low-expansion mechanism of Fe-Ni-based low-expansion alloy, early theories attribute to a special non-collinear-collinear magnetic phase transition. The theory assumes that as the temperature decreases, the face-centered cubic (FCC) structure of the alloy transforms from a small volume low-spin state of non-collinear magnetic structure to a large volume high-spin state of collinear magnetic structure, and the resulting negative expansion effect offsets the positive expansion caused by lattice anharmonic vibration, thereby achieving low expansion in a wide temperature range. However, subsequent neutron scattering experiments failed to confirm the existence of non-collinear magnetic structure, so the theoretical model lacks experimental support. In recent years, research has revealed that there are a large number of pre-martensite nanodomains in the parent phase of Fe-Ni-based low-expansion alloy, which gradually grow during cooling and exhibit negative expansion characteristics, effectively compensating for the positive expansion caused by lattice anharmonic vibration in the parent phase, thereby achieving the low-expansion effect of the alloy. At the same time, the gradual softening of the elastic modulus of the parent phase and the hardening of the modulus caused by the vibration anharmonicity of the nanodomains during cooling offset each other, resulting in a constant elastic modulus of the alloy in a wide temperature range. Therefore, it is challenging to simultaneously achieve Invar effect and Elinvar effect in a specific composition of Fe-Ni-based alloy. SUMMARY

[0004] (I) Invention purposes

[0005] The application aims to provide a low-expansion constant modulus alloy and a preparation method thereof, which changes the microstructure of the alloy through doping of elements, realizes a controllable low-expansion coefficient, and has the characteristics of constant modulus, and can realize Invar effect and Elinvar effect at the same time.

[0006] The technical scheme

[0007] To solve the above problems, the first aspect of the application provides a preparation method of a low-expansion constant modulus alloy, which is prepared by doping elements Cr and Cu in a Fe-Ni-Co-based alloy, and the chemical general formula of the low-expansion constant modulus alloy is Fe 54-2x Ni 23-2x Co 17 Cr 6+x Cu 3x , 0≤x≤2, and the method comprises the following steps:

[0008] Fe, Ni, Co, Cr and Cu are weighed according to preset weight percentages respectively, mixed uniformly, and a first material is obtained;

[0009] The first material is placed in an electric arc furnace, vacuumized and filled with inert gas, and repeatedly melted for at least 5 times to obtain an alloy ingot;

[0010] The alloy ingot is hot-rolled into a plate to obtain a low-expansion constant modulus alloy.

[0011] Further, the addition amount of Fe is 50-54wt%, the addition amount of Ni is 19-23wt%, and the addition amount of Co is 17wt%.

[0012] Further, the addition amount of Cr is 6-8wt%.

[0013] Further, the addition amount of Cu is 0-6wt%.

[0014] Further, the vacuum degree in the electric arc furnace is ≤4.5×10 -3 Pa.

[0015] Further, argon gas is introduced into the electric arc furnace as a protective gas, and the purity of the argon gas is 99.95%-99.99%.

[0016] Further, the melting current is 100A-230A.

[0017] Further, the hot-rolling temperature is 900℃-1000℃.

[0018] The second aspect of the present application provides a low expansion constant modulus alloy, which is obtained by the preparation method of any one of the low expansion constant modulus alloys described in the above description, and has a general chemical formula of Fe 54-2x Ni 23-2x Co 17 Cr 6+x Cu 3x , 0≤x≤2, and the weight percentages of the components are as follows: Fe is 50-54wt%, Ni is 19-23wt%, Co is 17wt%, Cr is 6-8wt%, and Cu is 0-6wt%.

[0019] Further, the modulus of the low expansion alloy does not change with temperature in the temperature range of-150℃ to 150℃, and the average expansion coefficient of the alloy in the range of-125℃ to 125℃ is 2×10 -6 / ℃ to 8×10 -6 / ℃.

[0020] (Three) beneficial effects

[0021] The above technical solutions of the present application have the following beneficial technical effects: the present application provides a low expansion constant modulus alloy and a preparation method thereof. In actual scenarios, Invar effect and Elinvar effect generally cannot coexist in Fe-Ni-based alloys with specific components. Therefore, the present application introduces point defects to optimize the microstructure of Fe-Ni-Co-based alloys, thereby realizing a new approach for coexistence of Invar effect and Elinvar effect or optimizing material performance. Point defects refer to the deviation or absence of atoms or ions in the material, resulting in the incompleteness of local structure. The present application introduces a large number of such local structure incompleteness by doping point defects in the martensitic transformation alloy, i.e., doping Cr and Cu elements in the Fe-Ni-Co-based alloy, to change the microstructure of the alloy. The low expansion constant modulus alloy has a general chemical formula of Fe 54-2x Ni 23- 2x Co 17 Cr 6+x Cu 3x, 0≤x≤2, by controlling the weight percentage of Cr and Cu elements in the mixed material, the formation of macro martensite domains can be inhibited, at the same time a large number of nano martensite domains are induced, so as to form a strain glass state, change the microstructure and optimize the thermal expansion performance. The method further comprises: repeatedly melting the mixed material in an arc smelting furnace into an ingot, and then performing hot rolling treatment, by controlling the current, vacuum degree and hot rolling temperature of smelting, the low expansion constant modulus alloy prepared realizes the adjustable low expansion coefficient, and the alloy has the characteristics of constant modulus. The present application obtains a series of adjustable low expansion coefficient alloys in a wide temperature range through element doping modification means, at the same time, the phenomenon of energy storage modulus not changing with temperature appears in a wide temperature range, that is, the Elinvar effect, thereby expanding the application scenarios of the expansion alloy. The preparation process of the present application is simple, efficient and easy to realize large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the elastic modulus test result of the low expansion constant modulus alloy of the embodiment 1 of the present application (x=0);

[0023] Figure 2 is the elastic modulus test result of the low expansion constant modulus alloy of the embodiment 2 of the present application (x=1 / 2);

[0024] Figure 3 is the elastic modulus test result of the low expansion constant modulus alloy of the embodiment 3 of the present application (x=1);

[0025] Figure 4 is the elastic modulus test result of the low expansion constant modulus alloy of the embodiment 4 of the present application (x=4 / 3);

[0026] Figure 5 is the elastic modulus test result of the low expansion constant modulus alloy of the embodiment 5 of the present application (x=3 / 2);

[0027] Figure 6 is the elastic modulus test result of the low expansion constant modulus alloy of the embodiment 6 of the present application (x=5 / 3);

[0028] Figure 7 is the elastic modulus test result of the low expansion constant modulus alloy of the embodiment 7 of the present application (x=2);

[0029] Figure 8 is the length change test result of the low expansion constant modulus alloy of the embodiments 1-7 of the present application;

[0030] Figure 9 is the thermal expansion coefficient test result of the low expansion constant modulus alloy of the embodiment 1 of the present application (x=0);

[0031] Figure 10is the thermal expansion coefficient test result of the low-expansion constant modulus alloy of embodiment 2 of the present application (x = 1 / 2);

[0032] Figure 11 is the thermal expansion coefficient test result of the low-expansion constant modulus alloy of embodiment 3 of the present application (x = 1);

[0033] Figure 12 is the thermal expansion coefficient test result of the low-expansion constant modulus alloy of embodiment 4 of the present application (x = 4 / 3);

[0034] Figure 13 is the thermal expansion coefficient test result of the low-expansion constant modulus alloy of embodiment 5 of the present application (x = 3 / 2);

[0035] Figure 14 is the thermal expansion coefficient test result of the low-expansion constant modulus alloy of embodiment 6 of the present application (x = 5 / 3);

[0036] Figure 15 is the thermal expansion coefficient test result of the low-expansion constant modulus alloy of embodiment 7 of the present application (x = 2). DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the present application clearer and more comprehensible, the present application will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0038] In the prior art, in Fe-Ni-based alloys with specific compositions, Invar effect and Elinvar effect generally cannot appear at the same time. For this reason, the present application proposes an innovative strategy, that is, doping high concentration of point defects in a martensitic transformation alloy to inhibit the formation of macroscopic martensitic domains, while inducing the formation of a large number of nanometer martensitic domains, forming a strain glass state, thereby optimizing the thermal expansion performance of the alloy. The present application aims to develop a new type of low-expansion constant modulus alloy and a preparation method thereof to meet the urgent needs of high-performance materials in the fields of precision instruments, aerospace, etc. The present application specifically includes:

[0039] I. Low-expansion constant modulus alloy and preparation method thereof

[0040] The first aspect of the present application provides a preparation method of a low-expansion constant modulus alloy, which is prepared by doping elements Cr and Cu in a Fe-Ni-Co-based alloy, and the chemical general formula of the low-expansion constant modulus alloy is Fe 54-2x Ni 23-2x Co 17 Cr6+x Cu 3x , 0≤x≤2, the method comprising:

[0041] S1, Fe, Ni, Co, Cr and Cu are weighed according to preset weight percentages respectively, mixed uniformly to obtain a first material (mixed material). During mixing, the addition amount of Fe is 50-54wt%, the addition amount of Ni is 19-23wt%, the addition amount of Co is 17wt%, the addition amount of Cr is 6-8wt%, and the addition amount of Cu is 0-6wt%.

[0042] S2, the first material is placed in an arc melting furnace for repeated melting for at least 5 times to obtain an alloy ingot. Specifically, the mixed material is placed in the arc melting furnace, vacuum is extracted to a preset vacuum degree, then inert gas is filled for repeated melting, the preset vacuum degree in the arc melting furnace is ≤4.5×10 -3 Pa, so as to prevent metal oxidation and improve the purity of the alloy. Argon gas is introduced into the arc melting furnace as a protective gas, the purity of the argon gas is 99.95%-99.99%, for example, 99.99%, and the melting current is 100A-230A.

[0043] S3, the alloy ingot is hot-rolled into a plate to obtain a low-expansion constant modulus alloy, and the hot-rolling temperature is 900℃-1000℃.

[0044] The second aspect of the application provides a low-expansion constant modulus alloy, which is obtained by the preparation method of any one of the low-expansion constant modulus alloys described above, and the chemical general formula of the low-expansion constant modulus alloy is Fe 54-2x Ni 23-2x Co 17 Cr 6+x Cu 3x , 0≤x≤2, the weight percentages of the elements are as follows: Fe is 50-54wt%, Ni is 19-23wt%, Co is 17wt%, Cr is 6-8wt%, and Cu is 0-6wt%. The modulus of the low-expansion alloy does not change with temperature in the temperature range of-150℃-150℃, and the average expansion coefficient of the alloy in the range of-125℃-125℃ is 2×10 -6 / ℃-8×10 -6 / ℃. II. Specific embodiments

[0046] Example 1

[0047] According to Fe 54 Ni 23 Co 17The weight percentage of Cr6(x=0) is calculated, and Fe, Ni, Co, and Cr are weighed and mixed uniformly, wherein the addition amount of Cr is 6wt%, and the addition amount of Fe, Ni, and Co is 54wt%, 23wt%, and 17wt% respectively, to obtain a first material; the first material is placed into an electric arc furnace and vacuum extraction is performed until the vacuum degree is less than 4.5×10 -3 Pa, then argon gas (with a purity of 99.99%) is filled, the current of the smelting is controlled to be 100-230A, the alloy ingot is obtained after smelting for 5 times, and then the alloy ingot is hot-rolled into a plate, the hot-rolling temperature is 1000℃, to obtain a low-expansion constant-modulus alloy. In order to detect the actual performance of the obtained low-expansion constant-modulus alloy, the low-expansion constant-modulus alloy is cut into an elongated strip required for testing by using an electric spark cutting machine, to obtain a test sample.

[0048] Example 2

[0049] According to Fe 53 Ni 22 Co 17 Cr 6.5 Cu 1.5 (x=1 / 2) weight percentage, Fe, Ni, Co, Cr and Cu are weighed and mixed uniformly, wherein the addition amount of Cr is 6.5wt%, the addition amount of Cu is 1.5wt%, the addition amount of Fe, Ni, and Co is 53wt%, 22wt%, and 17wt% respectively, to obtain a first material; the first material is placed into an electric arc furnace and vacuum extraction is performed until the vacuum degree is less than 4.5×10 -3 Pa, then argon gas (with a purity of 99.99%) is filled, the current of the smelting is controlled to be 100-230A, the alloy ingot is obtained after smelting for 5 times, and then the alloy ingot is hot-rolled into a plate, the hot-rolling temperature is 1000℃, to obtain a low-expansion constant-modulus alloy. In order to detect the actual performance of the obtained low-expansion constant-modulus alloy, the low-expansion constant-modulus alloy is cut into an elongated strip required for testing by using an electric spark cutting machine, to obtain a test sample.

[0050] Example 3

[0051] According to Fe 52 Ni 21 Co 17 Cr7Cu3(x=1) weight percentage, Fe, Ni, Co, Cr and Cu are weighed and mixed uniformly, wherein the addition amount of Cr is 7wt%, the addition amount of Cu is 3wt%, the addition amount of Fe, Ni, and Co is 52wt%, 21wt%, and 17wt% respectively, to obtain a first material; the first material is placed into an electric arc furnace and vacuum extraction is performed until the vacuum degree is less than 4.5×10 -3Pa, and then filled with argon (purity of 99.99%), control the current of smelting is 100~230A, smelting 5 times after the alloy ingot, then the alloy ingot hot rolling into plate, hot rolling temperature is 1000℃, get low expansion constant modulus alloy. In order to detect the actual performance of the low expansion constant modulus alloy, it is cut into the test required by the spark cutting machine into the slender strip, obtain test sample.

[0052] Example 4

[0053] According to Fe 154 / 3 Ni 61 / 3 Co 17 Cr 22 / 3 Cu4(x=4 / 3) weight percentage, respectively, Fe, Ni, Co, Cr and Cu element preparation mixed evenly, wherein the amount of Cr is 22 / 3wt%, the amount of Cu is 4wt%, the amount of Fe, Ni, Co is 154 / 3wt%, 61 / 3wt%, 17wt%, after mixing, get the first material; the first material into the electric arc furnace and extract the vacuum to less than 4.5×10 -3 Pa, and then filled with argon (purity of 99.99%), control the current of smelting is 100~230A, smelting 5 times after the alloy ingot, then the alloy ingot hot rolling into plate, hot rolling temperature is 1000℃, get low expansion constant modulus alloy. In order to detect the actual performance of the low expansion constant modulus alloy, it is cut into the test required by the spark cutting machine into the slender strip, obtain test sample.

[0054] Example 5

[0055] According to Fe 51 Ni 20 Co 17 Cr 7.5 Cu 4.5 (x=3 / 2) weight percentage, respectively, Fe, Ni, Co, Cr and Cu element preparation mixed evenly, wherein the amount of Cr is 7.5wt%, the amount of Cu is 4.5wt%, the amount of Fe, Ni, Co is 51wt%, 20wt%, 17wt%, after mixing, get the first material; the first material into the electric arc furnace and extract the vacuum to less than 4.5×10 -3 Pa, and then filled with argon (purity of 99.99%), control the current of smelting is 100~230A, smelting 5 times after the alloy ingot, then the alloy ingot hot rolling into plate, hot rolling temperature is 1000℃, get low expansion constant modulus alloy. In order to detect the actual performance of the low expansion constant modulus alloy, it is cut into the test required by the spark cutting machine into the slender strip, obtain test sample.

[0056] Example 6

[0057] According to Fe 152 / 3 Ni 59 / 3 Co 17 Cr 23 / 3 Cu5(x=5 / 3) weight percentage, respectively, Fe, Ni, Co, Cr and Cu elements are weighed and mixed uniformly, wherein the addition amount of Cr is 23 / 3wt%, the addition amount of Cu is 5wt%, the addition amounts of Fe, Ni and Co are 152 / 3wt%, 59 / 3wt% and 17wt% respectively, and after mixing, a first material is obtained; the first material is placed into an electric arc furnace and vacuum extraction is performed until the vacuum degree is less than 4.5x10 -3 Pa, then argon gas (purity is 99.99%) is filled, the current of smelting is controlled to be 100-230A, after smelting for 5 times, an alloy ingot is obtained, the alloy ingot is hot-rolled into a plate material, the hot-rolling temperature is 1000℃, and a low-expansion constant-modulus alloy is obtained. In order to detect the actual performance of the obtained low-expansion constant-modulus alloy, the low-expansion constant-modulus alloy is cut into an elongated strip required for testing by using an electric spark cutting machine, and a test sample is obtained.

[0058] Example 7

[0059] According to Fe 50 Ni 19 Co 17 Cr8Cu6(x=2) weight percentage, respectively, Fe, Ni, Co, Cr and Cu elements are weighed and mixed uniformly, wherein the addition amount of Cr is 8wt%, the addition amount of Cu is 6wt%, the addition amounts of Fe, Ni and Co are 50wt%, 19wt% and 17wt% respectively, and after mixing, a first material is obtained; the first material is placed into an electric arc furnace and vacuum extraction is performed until the vacuum degree is less than 4.5x10 -3 Pa, then argon gas (purity is 99.99%) is filled, the current of smelting is controlled to be 100-230A, after smelting for 5 times, an alloy ingot is obtained, the alloy ingot is hot-rolled into a plate material, the hot-rolling temperature is 1000℃, and a low-expansion constant-modulus alloy is obtained. In order to detect the actual performance of the obtained low-expansion constant-modulus alloy, the low-expansion constant-modulus alloy is cut into an elongated strip required for testing by using an electric spark cutting machine, and a test sample is obtained.

[0060] The relationship between the modulus and the temperature change of each test sample in the above examples (cut into an elongated strip with a size of 40x0.9x1.2mm by an electric spark line cutting machine) and the relationship between the length change amount and the temperature change (cut into an elongated strip with a size of 20x0.4x0.5mm by an electric spark line cutting machine) are detected respectively. The process parameters and the detection results of each example are shown in Table 1. The results show that a series of alloys with adjustable expansion coefficients and Elinvar effect can be obtained by using the preparation method of the present application. The average expansion coefficient of the alloy system of the present application can be adjusted from 2x10 -6 / ℃ to 8x10 -6 / ℃ in the range of-125℃ to 125℃. Referring to the accompanying drawings, Figures 1-15 in the wide temperature range of-150℃ to 150℃, the elastic modulus of the alloy does not change with temperature, that is, the Elinvar effect.

[0061] Table 1 Process parameters and detection results of each example

[0062]

[0063] In this example, seven composition samples with x=0, 1 / 2, 1, 4 / 3, 3 / 2, 5 / 3 and 2 are selected for modulus testing, in which the frequency is 1Hz during the testing process, and the measurement results shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 are obtained respectively. As can be seen from the above figures, the storage modulus of Fe 54-2x Ni 23-2x Co 17 Cr 6+x Cu 3x alloy is almost unchanged in the wide temperature range of-150℃ to 150℃, which is independent of temperature, that is, the alloy prepared in this example has the Elinvar effect. At the same time, the thermal expansion performance of the seven composition samples with x=0, 1 / 2, 1, 4 / 3, 3 / 2, 5 / 3 and 2 is tested, and the measurement results shown in Figure 9 , Figure 10 , Figure 11 , Figure 12 , Figure 13 , Figure 14 and Figure 15 and the result of Figure 8 are obtained respectively. Among them, the expansion coefficient=length change amount / temperature. As can be clearly seen from Figure 8 , with the increase of x, the slope of the length change amount and the temperature curve becomes larger and larger, which shows that the expansion coefficient of the expansion alloy gradually increases. The expansion coefficient of the alloy is calculated to beFigures 9-15 Various measurement results of the alloy (FeNiCoCrCu alloy) show that the average thermal expansion coefficient of the alloy in the range of -125 DEG C to 125 DEG C is regulated from 2*10 54- 2x Ni 23-2x Co 17 Cr 6+x Cu 3x The average thermal expansion coefficient of the alloy (FeNiCoCrCu alloy) in the range of -125 DEG C to 125 DEG C is regulated from 2*10 -6 / ℃ to 8*10 -6 / ℃. The present application is prepared by the preparation method described above, and a series of alloys with adjustable expansion coefficient and Elinvar effect are obtained, the expansion coefficient of the alloy is 2*10 -6 / ℃ to 8*10 -6 / ℃, and the elastic modulus of the alloy does not change with temperature in the wide temperature range of -150 DEG C to 150 DEG C, that is, the Elinvar effect. The present application changes the microstructure of the alloy by doping elements, suppresses the formation of macro martensite domains, and induces a large number of nano martensite domains, realizes the adjustable low expansion coefficient, and the alloy has the characteristics of constant modulus, obtains a series of low expansion performance and constant modulus performance.

[0064] The present application provides a low expansion constant modulus alloy and a preparation method thereof, the chemical general formula of the alloy is Fe 54- 2x Ni 23-2x Co 17 Cr 6+x Cu 3x (0≤x≤2). By adding a certain amount of Cr and Cu elements in the Fe-Ni-Co-based alloy, according to the Fe 54-2x Ni 23-2x Co 17 Cr 6+x Cu 3x Chemical general formula, the raw materials of Fe, Ni, Co, Cr and Cu are prepared, the adding amount of Fe is controlled to be 50-54wt%, the adding amount of Ni is controlled to be 19-23wt%, the adding amount of Co is controlled to be 17wt%, the adding amount of Cr is controlled to be 6-8wt%, and the adding amount of Cu is controlled to be 0-6wt%, the method can suppress the formation of macro martensite domains, and induce a large number of nano martensite domains, so as to form a strain glass state, change the microstructure, and optimize the thermal expansion performance; the mixed material is placed in an arc melting furnace and vacuumized, the vacuum degree is ≤4.5*10 - 3Pa, and then argon is filled repeatedly for more than or equal to 5 times of melting, the alloy ingot is melted into an alloy ingot, and the melting current is 100A-230A; then the alloy ingot is hot-rolled into a plate, and the hot-rolling temperature is 900-1000 DEG C, and finally the low-expansion constant modulus alloy is prepared. In general Fe-Ni-Co-based alloy, Invar effect and Elinvar effect generally cannot appear at the same time, the present application dopes point defects in the martensitic phase change alloy to inhibit the formation of macroscopic martensitic domains, and at the same time induce a large number of nanometer martensitic domains, so as to form a strain glass state to change the microstructure, optimize the thermal expansion performance, and further develop low-expansion constant modulus alloy materials. Combined with Table 1 and the attached Figures 1-7 , the attached Figure 8 and the attached Figures 9-15 , it can be known that the expansion coefficient of the alloy system of the present application can be adjusted from 2*10 -6 / ℃ to 8*10 -6 / ℃, the low-expansion characteristic is maintained, the expansion alloy meeting the specified low-expansion coefficient value of the industry can be prepared; and the expansion alloy simultaneously has the characteristics of constant modulus, i.e. Elinvar effect, in a wide temperature range of-150 DEG C to 150 DEG C. It can be known from the results that the modulus of the low-expansion alloy does not change with temperature in the temperature range of-150 DEG C to 150 DEG C, and the average expansion coefficient of the alloy in the range of-125 DEG C to 125 DEG C is 2*10 -6 / ℃-8*10 -6 / ℃. The low-expansion constant modulus alloy prepared by the present application has simple and efficient preparation process, can realize large-scale production in the industry, and precisely meets the urgent needs of the precision instrument, aerospace and other industries for low-expansion constant modulus alloy.

[0065] Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the protection scope of the present application. In the description of the present application, it should be noted that the terms "first", "second", "third" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance. In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict. It should be understood that the above specific embodiments of the present application are only used for illustrative or explanatory purposes, and do not constitute a limitation on the present application. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present application shall be included in the protection scope of the present application. In addition, the claims of the present application are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries. The present application is described above with reference to the embodiments of the present application. However, these embodiments are only for illustrative purposes, and are not intended to limit the scope of the present application. The scope of the present application is defined by the appended claims and their equivalents. Without departing from the scope of the present application, those skilled in the art can make various substitutions and modifications, which should fall within the scope of the present application. Although the embodiments of the present application have been described in detail, it should be understood that various changes, substitutions and modifications can be made to the embodiments of the present application without departing from the spirit and scope of the present application. Obviously, the above embodiments are only examples for clear illustration, and are not a limitation on the embodiments. Based on the above description, those of ordinary skill in the art can make other different forms of changes or modifications. Here, it is not necessary or possible to exhaust all the embodiments. The obvious changes or modifications derived therefrom are still within the protection scope of the present application.

Claims

1. A method for preparing a low-expansion constant-modulus alloy, characterized in that, The low expansion constant modulus alloy is prepared by doping Fe-Ni-Co based alloys with Cr and Cu. The general chemical formula of the low expansion constant modulus alloy is Fe. 54-2x Ni 23- 2x Co 17 Cr 6+x Cu 3x 0 < x ≤ 2, the low expansion constant modulus alloy has a modulus that does not change with temperature in the temperature range of -150℃ to 150℃, and the average coefficient of thermal expansion of the alloy is 2 × 10⁻⁶ in the temperature range of -125℃ to 125℃. -6 / ℃~8×10 -6 / ℃, the amount of Fe added is 50≤Fe<54wt%, the amount of Ni added is 19≤Ni<23wt%, the amount of Co added is 17wt%, the amount of Cr added is 6<Cr≤8wt%, and the amount of Cu added is 0<Cu≤6wt%. The method includes: Fe, Ni, Co, Cr and Cu are weighed out according to the preset weight percentages, mixed evenly, and the first material is obtained. The first material is placed in an electric arc melting furnace, vacuumed and filled with inert gas, and repeatedly melted at least 5 times to obtain an alloy ingot. The alloy ingot is hot-rolled into a sheet to obtain a low expansion constant modulus alloy, wherein the hot rolling temperature is 900℃~1000℃.

2. The method for preparing a low-expansion constant-modulus alloy according to claim 1, characterized in that, The vacuum degree inside the electric arc melting furnace is ≤4.5×10⁻⁶. -3 Pa.

3. The method for preparing a low-expansion constant-modulus alloy according to claim 1, characterized in that, Argon gas is introduced into the electric arc melting furnace as a protective gas, and the purity of the argon gas is 99.95% to 99.99%.

4. The method for preparing a low-expansion constant-modulus alloy according to claim 1, characterized in that, The smelting current is 100A to 230A.

5. A low-expansion constant-modulus alloy, characterized in that, The low-expansion constant-modulus alloy is obtained by the preparation method of the low-expansion constant-modulus alloy according to any one of claims 1-4, and the general chemical formula of the low-expansion constant-modulus alloy is Fe. 54- 2x Ni 23-2x Co 17 Cr 6+x Cu 3x 0 < x ≤ 2, and the weight percentages of each component are as follows: 50 ≤ Fe < 54 wt%, 19 ≤ Ni < 23 wt%, Co 17 wt%, 6 < Cr ≤ 8 wt%, 0 < Cu ≤ 6 wt%. The low-expansion constant-modulus alloy exhibits no change in modulus with temperature within the temperature range of -150℃ to 150℃, and its average coefficient of thermal expansion is 2 × 10⁻⁶ within the temperature range of -125℃ to 125℃. -6 / ℃~8×10 -6 / ℃.

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