Low-expansion constant-modulus alloy and preparation method thereof

Abstract

The invention belongs to the technical field of materials, and discloses a low-expansion constant-modulus alloy and a preparation method thereof.According to the method, the low-expansion constant-modulus alloy is prepared by doping Fe-Ni-Co-based alloy with elements Cr and Cu, the chemical general formula of the low-expansion constant-modulus alloy is Fe54-2xNi23-2xCo17Cr6 + xCu3x, x is larger than or equal to 0 and smaller than or equal to 2, and x is larger than or equal to 0 and smaller than or equal to 1. The method comprises the following steps: respectively weighing Fe, Ni, Co, Cr and Cu in percentage by weight according to a chemical general formula, and uniformly mixing to obtain a first material; the first material is placed in an electric arc smelting furnace to be repeatedly smelted for at least five times, and an alloy cast ingot is obtained; and the alloy ingot is hot-rolled into a plate, and the low-expansion constant-modulus alloy is obtained. According to the method, through element doping, the microstructure of the alloy is changed, the adjustable low expansion coefficient is achieved, the alloy has the constant modulus characteristic, and a series of alloys with the low expansion performance and the constant modulus can be prepared through the method.

Description

Technical Field

[0001] The invention belongs to the technical field of materials, and in particular relates to a low expansion constant modulus alloy and a preparation method thereof. Background Art

[0002] Low expansion alloys refer to a class of alloy materials that exhibit a low expansion coefficient within a specific temperature range. In nature, most solid materials will undergo significant changes in volume or length with temperature fluctuations, that is, thermal expansion and contraction, and their elastic modulus tends to increase with decreasing temperature. For precision instruments operating under extreme environmental conditions, the dimensional changes of internal components and the temperature dependence of the elastic modulus may cause severe thermomechanical stress, which in turn causes system performance degradation or even catastrophic failure. Guillaume first observed a unique physical phenomenon in Fe-36Ni alloy, namely the low expansion characteristic (Invar effect). The alloy hardly changes in size with temperature over a wide temperature range, showing an extremely low thermal expansion coefficient. At the same time, he also found that the elastic modulus of the alloy remains constant over a wide temperature range (Elinvar effect). These characteristics make Fe-Ni-based low expansion alloys indispensable materials in high-tech fields such as instrument components, electronic component packaging, precision measuring equipment, liquefied natural gas (LNG) carriers, special transmission cables, and aerospace, with huge market demand and application potential.

[0003] Regarding the low expansion mechanism of Fe-Ni-based low expansion alloys, early theories attributed it 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 changes from a small volume low spin state of a non-collinear magnetic structure to a large volume high spin state of a collinear magnetic structure, and the resulting negative expansion effect offsets the positive expansion caused by the anharmonic vibration of the lattice, thereby achieving low expansion in a wide temperature range. However, subsequent neutron scattering experiments failed to confirm the existence of non-collinear magnetic structures, so the theoretical model lacks experimental support. In recent years, studies have revealed that there are a large number of pre-martensitic nanodomains in the parent phase of Fe-Ni-based low expansion alloys. These nanodomains gradually grow and show negative expansion characteristics during the cooling process, effectively compensating for the positive expansion caused by the anharmonic vibration of the parent phase lattice, thereby achieving the low expansion effect of the alloy. At the same time, the gradual softening of the elastic modulus of the parent phase offsets the modulus hardening caused by the vibration anharmonicity of the nanodomains during cooling, resulting in the elastic modulus of the alloy remaining constant in a wide temperature range. Therefore, it is challenging to realize both the Invar effect and the Elinvar effect in Fe-Ni based alloys with specific compositions. Summary of the invention

[0004] 1. Purpose of the invention The purpose of the present invention is to provide a low expansion constant modulus alloy and a preparation method thereof, wherein the method changes the microstructure of the alloy by doping elements, realizes an adjustable low expansion coefficient, and the alloy has the characteristics of constant modulus, and can realize both the Invar effect and the Elinvar effect. The preparation process of the present invention is simple, efficient, and easy to realize large-scale production.

[0005] (II) Technical solution In order to solve the above problems, the first aspect of the present invention provides a method for preparing a low expansion constant modulus alloy, wherein the low expansion constant modulus alloy is prepared by doping elements Cr and Cu in a Fe-Ni-Co based alloy, wherein the 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 method comprises: Weigh Fe, Ni, Co, Cr and Cu respectively according to preset weight percentages, mix them evenly, and obtain a first material; placing the first material in an arc melting furnace, evacuating the furnace and filling the furnace with inert gas, and repeatedly melting the furnace at least 5 times to obtain an alloy ingot; The alloy ingot is hot rolled into a plate to obtain a low expansion constant modulus alloy.

[0006] Furthermore, the amount of Fe added is 50-54wt%, the amount of Ni added is 19-23wt%, and the amount of Co added is 17wt%.

[0007] Furthermore, the added amount of Cr is 6-8wt%.

[0008] Furthermore, the added amount of Cu is 0-6wt%.

[0009] Furthermore, the vacuum degree in the arc melting furnace is ≤4.5×10 -3 Pa.

[0010] Furthermore, argon is introduced into the arc melting furnace as a protective gas, and the purity of the argon is 99.95% to 99.99%.

[0011] Furthermore, the smelting current is 100A-230A.

[0012] Furthermore, the hot rolling temperature is 900°C to 1000°C.

[0013] The second aspect of the present invention provides a low expansion constant modulus alloy, the low expansion constant modulus alloy is obtained by any one of the preparation methods of the low expansion constant modulus alloy described in the above description, and the 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 weight percentages of each component are as follows: Fe is 50~54wt%, Ni is 19~23wt%, Co is 17wt%, Cr is 6~8wt%, and Cu is 0~6wt%.

[0014] Furthermore, the modulus of the low expansion alloy does not change with temperature in the temperature range of -150°C to 150°C, and the average expansion coefficient of the alloy in the range of -125°C to 125°C is 2×10 -6 / ℃~8×10 -6 / ℃.

[0015] (III) Beneficial effects The above-mentioned technical scheme of the present invention has the following beneficial technical effects: The present invention provides a low expansion constant modulus alloy and a preparation method thereof. In actual scenarios, in Fe-Ni-based alloys with specific compositions, the Invar effect and the Elinvar effect are generally difficult to appear at the same time. Therefore, the present invention optimizes the microstructure of Fe-Ni-Co-based alloys by introducing point defects, so as to achieve a new way for the coexistence of the Invar effect and the Elinvar effect or optimize material properties. Point defects refer to the deviation or absence of the position of atoms or ions in the material, resulting in local structural incompleteness. The present invention introduces a large amount of such local structural imperfections to change the microstructure of the alloy by doping point defects in the martensitic phase change alloy, that is, doping Cr and Cu elements in the Fe-Ni-Co-based alloy. 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, by controlling the weight percentage of Cr and Cu elements in the mixture, the formation of macroscopic martensite domains can be suppressed, and a large number of nano-martensite domains can be induced, thereby forming a strain glass state, changing the microstructure, and optimizing its thermal expansion performance. The method also includes: placing the mixed material in an arc melting furnace and repeatedly melting it into an ingot, and then hot rolling it. By controlling the melting current, vacuum degree, and hot rolling temperature, the prepared low expansion constant modulus alloy achieves an adjustable low expansion coefficient, and the alloy has the characteristics of constant modulus. The present invention obtains a series of adjustable low expansion coefficient alloys in a wide temperature range through element doping modification means, and at the same time, the storage modulus does not change with temperature in the wide temperature range, that is, the Elinvar effect, thereby broadening the application scenarios of expansion alloys. The preparation process of the present invention is simple and efficient, and it is easy to achieve large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the elastic modulus test result of the low expansion constant modulus alloy of Example 1 of the present invention (x=0); Figure 2 is the elastic modulus test result of the low expansion constant modulus alloy of Example 2 of the present invention (x=1 / 2); Figure 3 is the elastic modulus test result of the low expansion constant modulus alloy of Example 3 of the present invention (x=1); Figure 4 is the elastic modulus test result of the low expansion constant modulus alloy of Example 4 of the present invention (x=4 / 3); Figure 5 is the elastic modulus test result of the low expansion constant modulus alloy of Example 5 of the present invention (x=3 / 2); Figure 6 is the elastic modulus test result of the low expansion constant modulus alloy of Example 6 of the present invention (x=5 / 3); Figure 7 is the elastic modulus test result of the low expansion constant modulus alloy of Example 7 of the present invention (x=2); Figure 8 is the length variation test result of the low expansion constant modulus alloy of Examples 1-7 of the present invention; Fig. 9 is the test result of the thermal expansion coefficient of the low expansion constant modulus alloy of Example 1 of the present invention (x=0); Fig.10 is the test result of the thermal expansion coefficient of the low expansion constant modulus alloy of Example 2 of the present invention (x=1 / 2); Fig.11 is the test result of the thermal expansion coefficient of the low expansion constant modulus alloy of Example 3 of the present invention (x=1); Fig.12is the test result of the thermal expansion coefficient of the low expansion constant modulus alloy of Example 4 of the present invention (x=4 / 3); Fig.13 is the test result of the thermal expansion coefficient of the low expansion constant modulus alloy of Example 5 of the present invention (x=3 / 2); Fig.14 is the test result of the thermal expansion coefficient of the low expansion constant modulus alloy of Example 6 of the present invention (x=5 / 3); Fig.15 This is the test result of the thermal expansion coefficient of the low expansion constant modulus alloy of Example 7 of the present invention (x=2). DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. 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 invention.

[0018] In the prior art, in Fe-Ni based alloys with specific compositions, it is generally difficult for the Invar effect and the Elinvar effect to appear at the same time. To this end, the present invention proposes an innovative strategy, namely, doping a high concentration of point defects in the martensitic phase change alloy to suppress the formation of macroscopic martensitic domains, while inducing the formation of a large number of nano-martensitic domains to form a strained glass state, thereby optimizing the thermal expansion properties of the alloy. The present invention aims to develop a new low expansion constant modulus alloy and a preparation method thereof to meet the urgent demand for high-performance materials in the fields of precision instruments, aerospace, etc. The present invention specifically includes: 1. Low expansion constant modulus alloy and preparation method thereof The first aspect of the present invention provides a method for preparing a low expansion constant modulus alloy, wherein the low expansion constant modulus alloy is prepared by doping elements Cr and Cu in a Fe-Ni-Co based alloy, wherein the 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 method comprises: S1, Fe, Ni, Co, Cr and Cu are weighed respectively according to preset weight percentages, and mixed evenly to obtain a first material (mixed material). During mixing, the amount of Fe added is 50-54wt%, the amount of Ni added is 19-23wt%, the amount of Co added is 17wt%, the amount of Cr added is 6-8wt%, and the amount of Cu added is 0-6wt%.

[0019] S2, placing the first material in an arc melting furnace and repeatedly melting it for at least 5 times to obtain an alloy ingot. Specifically, the prepared mixed material is placed in an arc melting furnace and vacuumed to a preset vacuum degree, and then inert gas is filled in for repeated melting, and the preset vacuum degree in the arc melting furnace is ≤4.5×10 -3 Pa, to prevent metal oxidation and thus improve the purity of the alloy. Argon is introduced into the arc melting furnace as a protective gas, the purity of the argon is 99.95% to 99.99%, for example, 99.99%, and the melting current is 100A to 230A.

[0020] S3, hot rolling the alloy ingot into a plate to obtain a low expansion constant modulus alloy, wherein the hot rolling temperature is 900°C to 1000°C.

[0021] The second aspect of the present invention provides a low expansion constant modulus alloy, the low expansion constant modulus alloy is obtained by any one of the methods for preparing the low expansion constant modulus alloy described above, and the 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 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℃ to 150℃, and the average expansion coefficient of the alloy in the range of -125℃ to 125℃ is 2×10 -6 / ℃~8×10 -6 / ℃.

[0022] 2. Embodiment Example 1 According to Fe 54 Ni 23 Co 17 The weight percentage of Cr6 (x=0) is calculated, Fe, Ni, Co, and Cr are weighed and mixed evenly, wherein the amount of Cr added is 6wt%, and the amounts of Fe, Ni, and Co added are 54wt%, 23wt%, and 17wt%, respectively, and the first material is obtained after mixing; the first material is placed in an arc melting furnace and vacuum is drawn to a vacuum degree of less than 4.5×10 -3 Pa, then filled with argon (purity of 99.99%), controlled the smelting current to be 100~230A, smelted 5 times to obtain alloy ingots, and then hot rolled the alloy ingots into plates at a hot rolling temperature of 1000℃ to obtain low expansion constant modulus alloys. In order to detect the actual performance of the obtained low expansion constant modulus alloy, it was cut into thin strips required for the test by an electric spark cutting machine to obtain test samples.

[0023] Example 2 According to Fe 53 Ni 22 Co 17 Cr 6.5 Cu 1.5 (x=1 / 2) weight percentage calculation, Fe, Ni, Co, Cr and Cu are weighed and mixed evenly, wherein the amount of Cr added is 6.5wt%, the amount of Cu added is 1.5wt%, the amounts of Fe, Ni and Co added are 53wt%, 22wt% and 17wt% respectively, and the first material is obtained after mixing; the first material is placed in an arc melting furnace and vacuum is drawn to a vacuum degree of less than 4.5×10 -3 Pa, then filled with argon (purity of 99.99%), controlled the smelting current to be 100~230A, smelted 5 times to obtain alloy ingots, and then hot rolled the alloy ingots into plates at a hot rolling temperature of 1000℃ to obtain low expansion constant modulus alloys. In order to detect the actual performance of the obtained low expansion constant modulus alloy, it was cut into thin strips required for the test by an electric spark cutting machine to obtain test samples.

[0024] Example 3 According to Fe 52 Ni 21 Co 17 Calculate the weight percentage of Cr7Cu3 (x=1), weigh Fe, Ni, Co, Cr and Cu respectively, mix them evenly, wherein the amount of Cr added is 7wt%, the amount of Cu added is 3wt%, the amounts of Fe, Ni and Co added are 52wt%, 21wt% and 17wt% respectively, and mix to obtain the first material; put the first material into an arc melting furnace and draw vacuum until the vacuum degree is less than 4.5×10 -3 Pa, then filled with argon (purity of 99.99%), controlled the smelting current to be 100~230A, smelted 5 times to obtain alloy ingots, and then hot rolled the alloy ingots into plates at a hot rolling temperature of 1000℃ to obtain low expansion constant modulus alloys. In order to detect the actual performance of the obtained low expansion constant modulus alloy, it was cut into thin strips required for the test by an electric spark cutting machine to obtain test samples.

[0025] Example 4 According to Fe 154 / 3 Ni 61 / 3 Co 17 Cr 22 / 3Cu4 (x=4 / 3) weight percentage calculation, Fe, Ni, Co, Cr and Cu single substances are weighed and mixed evenly, wherein the addition amount of Cr is 22 / 3wt%, the addition amount of Cu is 4wt%, the addition amount of Fe, Ni and Co is 154 / 3wt%, 61 / 3wt% and 17wt% respectively, and the first material is obtained after mixing; the first material is placed in an arc melting furnace and vacuum is drawn to a vacuum degree of less than 4.5×10 -3 Pa, then filled with argon (purity of 99.99%), controlled the smelting current to be 100~230A, smelted 5 times to obtain alloy ingots, and then hot rolled the alloy ingots into plates at a hot rolling temperature of 1000℃ to obtain low expansion constant modulus alloys. In order to detect the actual performance of the obtained low expansion constant modulus alloy, it was cut into thin strips required for the test by an electric spark cutting machine to obtain test samples.

[0026] Example 5 According to Fe 51 Ni 20 Co 17 Cr 7.5 Cu 4.5 (x=3 / 2) weight percentage calculation, Fe, Ni, Co, Cr and Cu are weighed and mixed evenly, wherein the amount of Cr added is 7.5wt%, the amount of Cu added is 4.5wt%, the amounts of Fe, Ni and Co added are 51wt%, 20wt% and 17wt% respectively, and the first material is obtained after mixing; the first material is placed in an arc melting furnace and vacuum is drawn to a vacuum degree of less than 4.5×10 -3 Pa, then filled with argon (purity of 99.99%), controlled the smelting current to be 100~230A, smelted 5 times to obtain alloy ingots, and then hot rolled the alloy ingots into plates at a hot rolling temperature of 1000℃ to obtain low expansion constant modulus alloys. In order to detect the actual performance of the obtained low expansion constant modulus alloy, it was cut into thin strips required for the test by an electric spark cutting machine to obtain test samples.

[0027] Example 6 According to Fe 152 / 3 Ni 59 / 3 Co 17 Cr 23 / 3 Cu5 (x=5 / 3) weight percentage calculation, Fe, Ni, Co, Cr and Cu single substances are weighed and mixed evenly, wherein the addition amount of Cr is 23 / 3wt%, the addition amount of Cu is 5wt%, the addition amount of Fe, Ni and Co is 152 / 3wt%, 59 / 3wt% and 17wt% respectively, and the first material is obtained after mixing; the first material is placed in an arc melting furnace and vacuum is drawn to a vacuum degree of less than 4.5×10 -3Pa, then filled with argon (purity of 99.99%), controlled the smelting current to be 100~230A, smelted 5 times to obtain alloy ingots, and then hot rolled the alloy ingots into plates at a hot rolling temperature of 1000℃ to obtain low expansion constant modulus alloys. In order to detect the actual performance of the obtained low expansion constant modulus alloy, it was cut into thin strips required for the test by an electric spark cutting machine to obtain test samples.

[0028] Example 7 According to Fe 50 Ni 19 Co 17 Calculate the weight percentage of Cr8Cu6 (x=2), weigh Fe, Ni, Co, Cr and Cu respectively, mix them evenly, wherein the amount of Cr added is 8wt%, the amount of Cu added is 6wt%, the amounts of Fe, Ni and Co added are 50wt%, 19wt% and 17wt% respectively, and mix to obtain the first material; put the first material into an arc melting furnace and draw vacuum until the vacuum degree is less than 4.5×10 -3 Pa, then filled with argon (purity of 99.99%), controlled the smelting current to be 100~230A, smelted 5 times to obtain alloy ingots, and then hot rolled the alloy ingots into plates at a hot rolling temperature of 1000℃ to obtain low expansion constant modulus alloys. In order to detect the actual performance of the obtained low expansion constant modulus alloy, it was cut into thin strips required for the test by an electric spark cutting machine to obtain test samples.

[0029] The relationship between the modulus and temperature of each test sample in the above embodiment (cut into slender strips with a size of 40×0.9×1.2 mm by a wire-cut electric discharge machine) and the relationship between the length change and temperature (cut into slender strips with a size of 20×0.4×0.5 mm by a wire-cut electric discharge machine) were respectively tested. The process parameters and test results of each embodiment 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 invention. The alloy system of the present invention realizes that the average expansion coefficient of the expansion alloy can be adjusted from 2×10 -6 / ℃ adjusted to 8×10 -6 / ℃; and refer to the attached Figure 1-15 In the wide temperature range of -150°C to 150°C, the elastic modulus of the alloy does not change with temperature, which is the Elinvar effect.

[0030] Table 1 Process parameters and test results of various embodiments In this example, seven samples with x=0, 1 / 2, 1, 4 / 3, 3 / 2, 5 / 3, and 2 were selected for modulus testing. The test frequency was 1 Hz, and the results were Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The measurement results are shown. As can be seen from the above figure, Fe 54-2x Ni 23-2x Co 17 Cr 6+x Cu 3x The storage modulus of the alloy is almost unchanged in the wide temperature range of -150℃ to 150℃, and is independent of temperature, that is, the alloy prepared in this example has the Elinvar effect. At the same time, this example selected 7 samples with x=0, 1 / 2, 1, 4 / 3, 3 / 2, 5 / 3, 2 for thermal expansion performance testing, and the results were respectively Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.13 , Fig.14 and Fig.15 The measurement results shown and Figure 8 The result is: where expansion coefficient = length change / temperature. Figure 8 It can be clearly seen that as x increases, the slope of the curve of length change and temperature becomes larger and larger, which shows that the expansion coefficient of the expansion alloy gradually increases. After calculating the expansion coefficient of the alloy, we get Figure 9-Figure 15 Various measurement results, Fe 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℃ to 125℃ is reduced from 2×10 -6 / ℃~8×10 -6 / ℃ regulation. The present invention uses the above-mentioned preparation method to obtain a series of alloys with adjustable expansion coefficients and Elinvar effect. The expansion coefficient of the alloy is 2×10 -6 / ℃~8×10 -6 / ℃; and in a wide temperature range of -150℃ to 150℃, the elastic modulus of the alloy does not change with temperature, i.e., the Elinvar effect. The present invention changes the microstructure of the alloy by doping elements, inhibits the formation of macroscopic martensite domains, and induces a large number of nano-martensite domains, thereby achieving an adjustable low expansion coefficient, and the alloy has the characteristics of constant modulus, thereby obtaining a series of low expansion properties and constant modulus properties.

[0031] The present invention provides a low expansion constant modulus alloy and a preparation method thereof. The general chemical 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 to the Fe-Ni-Co based alloy, 54-2x Ni 23-2x Co 17 Cr 6+x Cu 3x The weight percentage of the chemical formula is as follows: Fe, Ni, Co, Cr and Cu are prepared as raw materials, and the addition amount of Fe is controlled to be 50-54wt%, the addition amount of Ni is controlled to be 19-23wt%, the addition amount of Co is controlled to be 17wt%, the addition amount of Cr is controlled to be 6-8wt%, and the addition amount of Cu is controlled to be 0-6wt%. By controlling the weight percentage of Cr and Cu elements in the mixed material, the method can inhibit the formation of macroscopic martensitic domains and induce a large number of nano-martensitic domains, thereby forming a strain glass state, changing the microstructure and optimizing its thermal expansion performance; the mixed material is placed in an arc melting furnace and evacuated, and the vacuum degree is ≤4.5×10 - 3 Pa, and then fill with argon gas and melt repeatedly for more than or equal to 5 times to melt into an alloy ingot, the melting current is 100A ~ 230A; then the alloy ingot is hot rolled into a plate, the hot rolling temperature is 900℃ ~ 1000℃, and finally a low expansion constant modulus alloy is prepared. In general Fe-Ni-Co based alloys, the Invar effect and the Elinvar effect are generally difficult to appear at the same time. The present invention dopes point defects in the martensitic phase change alloy to inhibit the formation of macroscopic martensitic domains and induce a large number of nano-martensitic domains, thereby forming a strain glass state change microstructure, optimizing its thermal expansion properties, and then developing a low expansion constant modulus alloy material. Combined with Table 1 and the attached Figure 1-7 , Attachment Figure 8 And attached Figure 9-15 It can be seen that the alloy system of the present invention realizes that the expansion coefficient of the expansion alloy can be increased from 2×10 -6 / ℃ adjusted to 8×10 -6 / ℃, maintaining the characteristics of low expansion, and can prepare expansion alloys that meet the industrial specified low expansion coefficient value; and the expansion alloy also has the characteristics of constant modulus in the wide temperature range of -150℃~150℃, that is, Elinvar effect. The results show that 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 / ℃. The low expansion constant modulus alloy prepared by the present invention has a simple and efficient preparation process, can realize industrial large-scale production, and accurately meets the urgent needs of precision instruments, aerospace and other industries for low expansion constant modulus alloys.

[0032] Obviously, the described embodiments are part of the embodiments of the present invention, but not all of them. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. It should be understood that the above-mentioned specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation on the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the scope of protection of the present invention. In addition, the claims attached to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries. The present invention is described above with reference to the embodiments of the present invention. However, these embodiments are for illustrative purposes only, not for limiting the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents. Without departing from the scope of the present invention, a variety of substitutions and modifications can be made by those skilled in the art, and these substitutions and modifications should fall within the scope of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications may be made to the embodiments of the present invention without departing from the spirit and scope of the present invention. Obviously, the above embodiments are merely examples for clear description and are not limitations on the embodiments. For those of ordinary skill in the art, other different forms of changes or modifications may be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived therefrom are still within the scope of protection created by the present invention.

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 the elements Cr and Cu in the Fe-Ni-Co based alloy. The 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 method comprises: Weigh Fe, Ni, Co, Cr and Cu respectively according to preset weight percentages, mix them evenly, and obtain a first material; placing the first material in an arc melting furnace, evacuating the furnace and filling the furnace with inert gas, and repeatedly melting the furnace at least 5 times to obtain an alloy ingot; The alloy ingot is hot rolled into a plate to obtain a low expansion constant modulus alloy.

2. The method for preparing a low expansion constant modulus alloy according to claim 1, characterized in that: The amount of Fe added is 50-54wt%, the amount of Ni added is 19-23wt%, and the amount of Co added is 17wt%.

3. The method for preparing a low expansion constant modulus alloy according to claim 1, characterized in that: The added amount of Cr is 6-8wt%.

4. The method for preparing a low expansion constant modulus alloy according to claim 1, characterized in that: The added amount of Cu is 0-6wt%.

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

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

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

8. The method for preparing a low expansion constant modulus alloy according to claim 1, characterized in that: The hot rolling temperature is 900°C to 1000°C.

9. 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 to 8, and the 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 weight percentages of each component are as follows: Fe is 50~54wt%, Ni is 19~23wt%, Co is 17wt%, Cr is 6~8wt%, and Cu is 0~6wt%.

10. A low expansion constant modulus alloy according to claim 9, characterized in that: The modulus of the low expansion alloy does not change with temperature in the temperature range of -150°C to 150°C, and the average expansion coefficient of the alloy in the range of -125°C to 125°C is 2×10 -6 / ℃~8×10 -6 / ℃.

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