High-temperature-resistant low-expansion alloy and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant low-expansion alloy and a preparation method thereof. The high-temperature-resistant low-expansion alloy is of an FCC single-phase structure. The average thermal expansion coefficient of the high-temperature-resistant low-expansion alloy at the temperature of 20-200 DEG C is 2 * 10 <-6 > / DEG C or below. The preparation method comprises the steps that raw materials are subjected to a cold crucible vacuum suspension smelting technology to obtain a mother alloy matrix, and then the mother alloy matrix is subjected to vacuum high-temperature annealing and heat treatment to prepare the high-temperature-resistant low-expansion alloy. In the smelting stage, cold crucible vacuum suspension smelting is adopted to replace traditional induction smelting, the preparation method is high in universality, the purity of an alloy matrix can be improved, the microstructure of the alloy is optimized, the lower thermal expansion coefficient is achieved at the high temperature under the condition that the alloy components are not changed, and the alloy performance is improved. Therefore, the use temperature range of the low-expansion alloy is expanded, and the stability of the alloy at high temperature can be better guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of high temperature resistant low expansion alloys, and in particular relates to a high temperature resistant low expansion alloy and a preparation method thereof. Background Art

[0002] Due to the limited purity of the raw materials, the low expansion alloy matrix contains many harmful elements such as S and P. In order to remove these harmful elements, some Mn, Si and other elements are often added to the matrix, and the harmful elements originally dissolved in the matrix are precipitated in the form of oxides and sulfides to purify the alloy matrix. The special Fe / Ni element ratio in the alloy matrix causes some reverse-spin Fe-Fe atomic pairs to exist inside it, resulting in a large spontaneous magnetostriction. The temperature increase within a certain range can offset part of the positive expansion caused by thermal vibration. However, the precipitates will affect the lattice constant to varying degrees and change the state of the reverse-spin Fe-Fe atomic pairs. This effect is particularly obvious at high temperatures. Therefore, during the temperature change process, the thermal expansion coefficient of the precipitates is greater than that of the matrix, which will increase the overall thermal expansion coefficient of the alloy and make the high temperature resistance characteristics insufficient.

[0003] At present, the traditional induction melting technology is often used to prepare low expansion alloys, and its main steps are charging, melting, refining, casting, cooling, etc. However, the traditional induction melting technology generally uses non-vacuum melting when melting low expansion alloys, which has the disadvantages of easy oxidation of the ingot surface, large segregation of the ingot structure, and difficulty in controlling the impurity content of the ingot. Therefore, how to keep the matrix of the low expansion alloy pure and the structure uniform is an urgent problem to be solved. Summary of the invention

[0004] The main purpose of the present invention is to provide a high temperature low expansion alloy and a preparation method thereof, so as to overcome the deficiencies of the prior art.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes: One aspect of the present invention provides a high temperature resistant low expansion alloy having an FCC single-phase structure; the average thermal expansion coefficient of the high temperature resistant low expansion alloy at 20-200°C is within 2×10 -6 / ℃ below.

[0006] Furthermore, the high temperature resistant low expansion alloy includes any one of a binary Fe-Ni alloy or a ternary Fe-Co-Ni alloy.

[0007] Another aspect of the present invention provides a method for preparing a high temperature resistant low expansion alloy, comprising: subjecting the raw materials to cold crucible vacuum suspension melting technology to obtain a master alloy matrix, and then subjecting the raw materials to vacuum high temperature annealing and heat treatment to obtain the high temperature resistant low expansion alloy.

[0008] Another aspect of the present invention provides a high temperature resistant low expansion alloy prepared by the preparation method.

[0009] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention adopts cold crucible vacuum suspension melting instead of traditional induction melting in the melting stage, so that the molten steel is prevented from introducing impurity elements in the crucible and maintaining the purity of the alloy matrix. The cold crucible vacuum suspension melting method has strong universality and can be applied to binary Fe-Ni low expansion alloys and ternary Fe-Co-Ni low expansion alloys.

[0010] (2) The present invention adopts suspension melting technology to improve the purity of the alloy matrix and optimize the microstructure of the alloy. Without changing the alloy composition, a lower thermal expansion coefficient is achieved at high temperature, thereby expanding the use temperature range of the low expansion alloy and better ensuring the stability of the alloy at high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 is a graph showing the test results of the thermal expansion coefficient of the low expansion alloy in some typical embodiments of the present invention; Figure 2 1 is an XRD characterization result diagram of low expansion alloys in some typical embodiments of the present invention; Figure 3 It is a schematic diagram of the electromagnetic suspension melting principle in the cold crucible vacuum suspension melting technology of the present invention; Figure 4 It is a schematic diagram of cold crucible suspension melting in the cold crucible vacuum suspension melting technology of the present invention; Figure 5 It is an equipment diagram of the cold crucible vacuum suspension melting technology of the present invention. DETAILED DESCRIPTION

[0013] In view of the problem that the above-mentioned existing low expansion alloys have insufficient high temperature resistance, the inventors of the present invention have conducted extensive and in-depth research and provided a high temperature low expansion alloy and a preparation method thereof. The cold crucible vacuum suspension melting technology is mainly used to eliminate the contamination of the impurity elements in the crucible to the molten steel during melting, so as to obtain a purer alloy matrix. After high temperature annealing, the alloy is processed into a device and subjected to special heat treatment to finally obtain a high temperature resistant low expansion alloy.

[0014] Suspension melting is divided into full suspension melting (without crucible) and cold crucible suspension melting. The former can only melt small samples of a few hundred grams, while the latter can do tens of kilograms. The cold crucible has cooling water inside the crucible to prevent the crucible from melting. The cold crucible vacuum suspension melting technology can avoid the presence of too many impurity precipitates in the alloy matrix, which plays a great role in improving the low expansion characteristics of the alloy. This technology is to place a petaled water-cooled crucible in an alternating electromagnetic field, use the eddy current heat generated by the electromagnetic field to melt the metal, and rely on the electromagnetic force to keep the molten metal in soft contact or non-contact with the crucible wall, thereby realizing the melting of the furnace charge. The advantage of this technology is that it eliminates the contamination of the crucible material to the melt under high temperature conditions, and the smelting process has strong electromagnetic stirring, which can obtain alloy ingots with uniform structure, and has high melting temperature, good product quality, and low scrap rate. It has been widely used in the smelting preparation of rare earth metal alloys, high-purity sputtering targets, high melting point metals, and intermetallic compounds with high composition accuracy requirements.

[0015] The technical solution, its implementation process and principle will be further explained as follows.

[0016] As one aspect of the technical solution of the present invention, a high temperature resistant low expansion alloy is provided, which has an FCC single-phase structure; the average thermal expansion coefficient of the high temperature resistant low expansion alloy at 20-200°C is 2×10 -6 / below ℃.

[0017] In some embodiments, the high temperature resistant low expansion alloy includes at least any one of a binary Fe-Ni alloy or a ternary Fe-Co-Ni alloy, but is not limited thereto.

[0018] In some embodiments, the average thermal expansion coefficient of the binary Fe-Ni alloy at 20-200°C is 1.5×10 -6 / ℃ below.

[0019] In some embodiments, the average thermal expansion coefficient of the ternary Fe-Co-Ni alloy at 20-200°C is within 2×10 -6 / ℃ below.

[0020] In some embodiments, the average thermal expansion coefficient of the high temperature resistant low expansion alloy at 20-100°C is within 2×10 -6 / ℃ below.

[0021] In some embodiments, the high temperature resistant low expansion alloy further includes trace elements that may be selectively added or not added, and the trace elements include any one or a combination of two or more of Cu, Nb, Ti, Zr, etc., but are not limited thereto.

[0022] In some embodiments, the content of matrix impurity elements in the high temperature resistant low expansion alloy is less than 100 PPM, and the matrix impurity elements include any one or a combination of two or more of C, S, P, Si, Mn, Al, Cr, Ca, etc., but are not limited to these.

[0023] As another aspect of the technical solution of the present invention, a method for preparing a high temperature resistant and low expansion alloy is provided, which comprises: subjecting the raw materials to a cold crucible vacuum suspension melting technique to obtain a master alloy matrix, and then subjecting the raw materials to vacuum high temperature annealing and heat treatment to obtain the high temperature resistant and low expansion alloy.

[0024] In some embodiments, the preparation method includes: preparing raw materials of a binary Fe-Ni alloy or a ternary Fe-Co-Ni alloy. The mass ratio of Fe to Ni in the binary Fe-Ni alloy is 63-65:35-37; the mass ratio of Co to Ni in the ternary Fe-Co-Ni alloy is 3-5:31-33, and the balance is iron.

[0025] In some embodiments, the preparation method comprises: preparing the raw materials through cold crucible vacuum levitation melting technology to obtain a master alloy matrix. The vacuum degree of the cold crucible vacuum levitation melting technology is less than 1×10 -3 Pa, the melting time is 0.2~1h, and the refining time is 1~5min. The specific process of the cold crucible vacuum suspension melting technology of the present invention includes: charging, vacuuming, melting, refining, cooling, and obtaining a master alloy matrix. The melting time of the melting process depends on multiple factors such as equipment power, raw material shape and size, raw material weight, equipment coil size, etc., and is generally 0.2~1h, and the refining time is 1~5min.

[0026] In some embodiments, the preparation method further comprises: -3 The alloy matrix is ​​homogenized by vacuum high temperature annealing at 1000-1200°C for 5-10 hours.

[0027] In some embodiments, the preparation method further comprises: heat treating the homogenized alloy matrix at 800-900° C. for 1-3 hours to prepare a high temperature resistant and low expansion alloy.

[0028] In some more specific embodiments, when preparing a binary Fe-Ni alloy, the preparation method may include the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and prepare the raw materials with a mass ratio of Fe:Ni=63~65:35~37; S2, using a cold crucible vacuum suspension melting device to perform melting to obtain a master alloy matrix; S3, using a high vacuum heat treatment furnace to perform high temperature annealing on the master alloy matrix, annealing at 1000-1100°C for 5-10 hours to obtain a homogenized alloy matrix. The specific process depends on the composition and size of the master alloy; S4, processing the homogenized alloy matrix to obtain the standard round rod (φ6mm*25mm) required for thermal expansion test, the disc (φ28mm*3mm) required for XRF test, and the disc (φ20mm*3mm) required for XRD test; S5, keeping the test sample at 800-900°C for 1-3 hours and then quenching and cooling it to obtain a high temperature resistant low expansion alloy.

[0029] In some more specific embodiments, when preparing a ternary Fe-Co-Ni alloy, the preparation method may include the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and prepare the raw materials with a mass ratio of Fe:Co:Ni=remainder:3~5:31~33; S2, using a cold crucible vacuum suspension melting device to perform melting to obtain a master alloy matrix; S3, using a high vacuum heat treatment furnace to perform high temperature annealing on the master alloy matrix, annealing at 1000-1100°C for 5-10 hours to obtain a homogenized alloy matrix. The specific process depends on the composition and size of the master alloy; S4, processing the homogenized alloy matrix to obtain the standard round rod (φ6mm*25mm) required for thermal expansion test, the disc (φ28mm*3mm) required for XRF test, and the disc (φ20mm*3mm) required for XRD test; S5, keeping the test sample at 800-900°C for 1-3 hours and then quenching and cooling it to obtain a high temperature resistant low expansion alloy.

[0030] As another aspect of the technical solution of the present invention, it also provides a high temperature resistant low expansion alloy prepared by the preparation method.

[0031] Specifically, the high temperature resistant low expansion alloy obtained by the present invention has the following characteristics: (1) The content of impurity elements (C, S, P, Si, Mn, Al, Cr, Ca, etc.) in the alloy matrix is ​​extremely low, less than 100 PPM, and there is no obvious impurity in the XRF full spectrum scan results; (2) The coefficient of thermal expansion (CTE) at 20~200℃ is extremely low, at 2×10 -6 / ℃ or less, significantly better than existing brands; (3) XRD characterization results show that the prepared alloy has an FCC single-phase structure without any impurities or second phases.

[0032] In summary, the present invention adopts cold crucible vacuum suspension melting instead of traditional induction melting in the melting stage, so that the molten steel avoids the introduction of impurity elements in the crucible and maintains the purity of the alloy matrix. This cold crucible vacuum suspension melting method has strong universality and can be applied to binary Fe-Ni low expansion alloys and ternary Fe-Co-Ni low expansion alloys. The low expansion alloy prepared by the present invention has a lower thermal expansion coefficient at a high temperature of 20~200℃, which is conducive to broadening the use temperature range of the low expansion alloy and better ensuring the stability of the device at high temperature.

[0033] 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 Examples and Comparative Examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention, without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.

[0034] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the art can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially. The commercial selection of the remaining raw materials and instruments not mentioned are all conventional selections and do not involve the core technical means of the present invention.

[0035] Example 1 A binary Fe-Ni low expansion alloy, the molar ratio of which is designed to be Fe a Ni b . Among them, a=64%, b=36%, that is, Fe 64 Ni 36 .

[0036] Binary Fe-Ni low expansion alloy Fe 64 Ni 36 The preparation method comprises the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and configure the raw materials according to the mass ratio of Fe:Ni=64:36; S2, placing the prepared raw materials in a cold crucible for suspension smelting, and wait for the vacuum degree to be less than 1×10 -3 Pa, argon gas is filled in the furnace to make the gas pressure in the furnace reach 0.05MPa, and then smelting is carried out, the melting time is about 0.5h, and the refining time is 2min. After cooling, the master alloy matrix is ​​obtained; S3, vacuum high temperature annealing of the master alloy matrix is ​​performed in a high vacuum heat treatment furnace, and the vacuum degree is less than 1×10 -3 Pa, annealing at 1100 °C for 10 h to obtain a homogenized alloy matrix; S4, processing the homogenized alloy matrix to obtain the standard round rod (φ6mm*25mm) required for thermal expansion test, the disc (φ28mm*3mm) required for XRF test, and the disc (φ20mm*3mm) required for XRD test; S5, keeping the test sample at 840° C. for 1 hour and then quenching and cooling it to obtain a binary system high temperature resistant and low expansion alloy.

[0037] The thermal expansion coefficient test results of the high temperature resistant low expansion alloy prepared by the method are shown in Figure 1 ; XRD characterization results are shown in Figure 2 .

[0038] Example 2 A binary Fe-Ni low expansion alloy, the molar ratio of which is designed to be Fe a Ni b . Among them, a=63%, b=37%, that is, Fe 63 Ni 37 .

[0039] Binary Fe-Ni low expansion alloy Fe 64 Ni 36 The preparation method comprises the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and configure the raw materials according to the mass ratio of Fe:Ni=63:37; S2, placing the prepared raw materials in a cold crucible for suspension smelting, and wait for the vacuum degree to be less than 1×10 -3 Pa, argon gas is filled in the furnace to make the gas pressure in the furnace reach 0.05MPa, and then smelting is carried out, the melting time is about 0.5h, and the refining time is 2min. After cooling, the master alloy matrix is ​​obtained; S3, vacuum high temperature annealing of the master alloy matrix is ​​performed in a high vacuum heat treatment furnace, and the vacuum degree is less than 1×10 -3 Pa, annealing at 1100 °C for 10 h to obtain a homogenized alloy matrix; S4, processing the homogenized alloy matrix to obtain the standard round rod (φ6mm*25mm) required for thermal expansion test, the disc (φ28mm*3mm) required for XRF test, and the disc (φ20mm*3mm) required for XRD test; S5, keeping the test sample at 840° C. for 1 hour and then quenching and cooling, so as to obtain a binary system high temperature resistant and low expansion alloy.

[0040] Example 3 A binary Fe-Ni low expansion alloy, the molar ratio of which is designed to be Fe a Ni b . Among them, a=65%, b=35%, that is, Fe65 Ni 35 .

[0041] Binary Fe-Ni low expansion alloy Fe 64 Ni 36 The preparation method comprises the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and configure the raw materials according to the mass ratio of Fe:Ni=63:37; S2, placing the prepared raw materials in a cold crucible for suspension smelting, and wait for the vacuum degree to be less than 1×10 -3 Pa, argon gas is filled in the furnace to make the gas pressure in the furnace reach 0.05MPa, and then smelting is carried out, the melting time is about 0.5h, and the refining time is 2min. After cooling, the master alloy matrix is ​​obtained; S3, vacuum high temperature annealing of the master alloy matrix is ​​performed in a high vacuum heat treatment furnace, and the vacuum degree is less than 1×10 -3 Pa, annealing at 1100 °C for 10 h to obtain a homogenized alloy matrix; S4, processing the homogenized alloy matrix to obtain the standard round rod (φ6mm*25mm) required for thermal expansion test, the disc (φ28mm*3mm) required for XRF test, and the disc (φ20mm*3mm) required for XRD test; S5, keeping the test sample at 840° C. for 1 hour and then quenching and cooling, so as to obtain a binary system high temperature resistant and low expansion alloy.

[0042] Example 4 A ternary Fe-Ni-Co low expansion alloy, the molar ratio of which is designed to be Fe a Ni b Co c . Among them, a=64%, b=32%, c=4%, that is, Fe 64 Ni 36 Co4.

[0043] Ternary Fe-Ni-Co low expansion alloy Fe 64 Ni 36 The preparation method of Co4 comprises the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and prepare the raw materials according to the mass ratio of Fe:Ni:Co=64:32:4; S2, placing the prepared raw materials in a cold crucible for suspension smelting, and wait for the vacuum degree to be less than 1×10 -3 After the furnace pressure reaches 0.05 MPa, argon is filled in, and melting is carried out. The melting time is about 0.5 h, and the refining time is 2 min. After cooling, a pure master alloy matrix is ​​obtained. S3, vacuum high temperature annealing of the master alloy matrix is ​​performed in a high vacuum heat treatment furnace, and the vacuum degree is less than 1×10 -3 Pa, annealing at 1050 °C for 5 h to obtain a homogenized alloy matrix; S4, processing the homogenized alloy matrix to obtain the standard round bar (φ6mm*25mm) required for the test, the disc (φ28mm*3mm) required for the XRF test, and the disc (φ20mm*3mm) required for the XRD test; S5, keeping the test sample at 840° C. for 1 hour and then quenching and cooling it to obtain a ternary high temperature resistant and low expansion alloy.

[0044] The thermal expansion coefficient test results of the high temperature resistant low expansion alloy prepared by the method are shown in Figure 1 ; XRD characterization results are shown in Figure 2 .

[0045] Example 5 A ternary Fe-Ni-Co low expansion alloy, the molar ratio of which is designed to be Fe a Ni b Co c . Among them, a=64%, b=31%, c=5%, that is, Fe 64 Ni 31 Co5.

[0046] Ternary Fe-Ni-Co low expansion alloy Fe 64 Ni 36 The preparation method of Co4 comprises the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and prepare the raw materials according to the mass ratio of Fe:Ni:Co=64:31:5; S2, placing the prepared raw materials in a cold crucible for suspension smelting, and wait for the vacuum degree to be less than 1×10 -3 After the furnace pressure reaches 0.05 MPa, argon is filled in, and melting is carried out. The melting time is about 0.5 h, and the refining time is 2 min. After cooling, a pure master alloy matrix is ​​obtained. S3, vacuum high temperature annealing of the master alloy matrix is ​​performed in a high vacuum heat treatment furnace, and the vacuum degree is less than 1×10 -3 Pa, annealing at 1050 °C for 5 h to obtain a homogenized alloy matrix; S4, processing the homogenized alloy matrix to obtain the standard round bar (φ6mm*25mm) required for the test, the disc (φ28mm*3mm) required for the XRF test, and the disc (φ20mm*3mm) required for the XRD test; S5, keeping the test sample at 840° C. for 1 hour and then quenching and cooling it to obtain a ternary high temperature resistant and low expansion alloy.

[0047] Example 6 A ternary Fe-Ni-Co low expansion alloy, the molar ratio of which is designed to be Fe a Ni b Co c . Among them, a=64%, b=33%, c=3%, that is, Fe 64 Ni 33 Co3.

[0048] Ternary Fe-Ni-Co low expansion alloy Fe 64 Ni 36 The preparation method of Co4 comprises the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and prepare the raw materials according to the mass ratio of Fe:Ni:Co=64:33:3; S2, placing the prepared raw materials in a cold crucible for suspension smelting, and wait for the vacuum degree to be less than 1×10 -3 After the furnace pressure reaches 0.05 MPa, argon is filled in, and melting is carried out. The melting time is about 0.5 h, and the refining time is 2 min. After cooling, a pure master alloy matrix is ​​obtained. S3, vacuum high temperature annealing of the master alloy matrix is ​​performed in a high vacuum heat treatment furnace, and the vacuum degree is less than 1×10 -3 Pa, annealing at 1050 °C for 5 h to obtain a homogenized alloy matrix; S4, processing the homogenized alloy matrix to obtain the standard round bar (φ6mm*25mm) required for the test, the disc (φ28mm*3mm) required for the XRF test, and the disc (φ20mm*3mm) required for the XRD test; S5, keeping the test sample at 840° C. for 1 hour and then quenching and cooling it to obtain a ternary high temperature resistant and low expansion alloy.

[0049] Example 7 A ternary Fe-Ni-Co low expansion alloy, the molar ratio of which is designed to be Fe a Ni b Co c . Among them, a=64%, b=32%, c=4%, that is, Fe 64 Ni 36 Co4.

[0050] Ternary Fe-Ni-Co low expansion alloy Fe 64 Ni 36 The preparation method of Co4 comprises the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and prepare the raw materials according to the mass ratio of Fe:Ni:Co=64:32:4; S2, placing the prepared raw materials in a cold crucible for suspension smelting, and wait for the vacuum degree to be less than 1×10 -3 Pa, argon is filled in the furnace to make the pressure in the furnace reach 0.05MPa, then smelting is carried out, the melting time is about 0.5h, refining is 1min, and the pure master alloy matrix is ​​obtained after cooling; S3, vacuum high temperature annealing of the master alloy matrix is ​​performed in a high vacuum heat treatment furnace, and the vacuum degree is less than 1×10 -3 Pa, annealing at 1050 °C for 5 h to obtain a homogenized alloy matrix; S4, processing the homogenized alloy matrix to obtain the standard round bar (φ6mm*25mm) required for the test, the disc (φ28mm*3mm) required for the XRF test, and the disc (φ20mm*3mm) required for the XRD test; S5, keeping the test sample at 840° C. for 1 hour and then quenching and cooling it to obtain a ternary high temperature resistant and low expansion alloy.

[0051] Example 8 A ternary Fe-Ni-Co low expansion alloy, the molar ratio of which is designed to be Fe a Ni b Co c . Among them, a=64%, b=32%, c=4%, that is, Fe 64 Ni 36 Co4.

[0052] Ternary Fe-Ni-Co low expansion alloy Fe 64 Ni 36 The preparation method of Co4 comprises the following steps: S1, polish and clean the raw materials, remove the surface oxide layer, and prepare the raw materials according to the mass ratio of Fe:Ni:Co=64:32:4; S2, placing the prepared raw materials in a cold crucible for suspension smelting, and wait for the vacuum degree to be less than 1×10 -3 Pa, argon is filled in the furnace to make the pressure in the furnace reach 0.05MPa, then smelting is carried out, the melting time is about 0.5h, refining is 5min, and a pure master alloy matrix is ​​obtained after cooling; S3, vacuum high temperature annealing of the master alloy matrix is ​​performed in a high vacuum heat treatment furnace, and the vacuum degree is less than 1×10 -3 Pa, annealing at 1050 °C for 5 h to obtain a homogenized alloy matrix; S4, processing the homogenized alloy matrix to obtain the standard round bar (φ6mm*25mm) required for the test, the disc (φ28mm*3mm) required for the XRF test, and the disc (φ20mm*3mm) required for the XRD test; S5, keeping the test sample at 840° C. for 1 hour and then quenching and cooling it to obtain a ternary high temperature resistant and low expansion alloy.

[0053] Comparative Example 1 Purchase a commercially available binary Fe-Ni low expansion alloy, grade 4J36, with a molar ratio of Fe a Ni b Among them, a=63~65%, b=35~37%, that is, Fe 63~65 Ni 35~37 .

[0054] Commercially available low expansion alloys are generally delivered in a forged state. According to YB / T 5241-2014, heat treatment is required to obtain good low expansion properties.

[0055] S1, process the commercially available 4J36 to obtain the standard round bar (φ6mm*25mm) required for thermal expansion test, the disc (φ28mm*3mm) required for XRF test, and the disc (φ20mm*3mm) required for XRD test; S2, for the above test samples, keep them at 840°C for 1 hour and then quench and cool them.

[0056] The thermal expansion coefficient test results of commercially available binary Fe-Ni low expansion alloys are shown in Figure 1 ; XRD characterization results are shown in Figure 2 .

[0057] Comparative Example 2 Purchase the commercially available ternary Fe-Ni-Co low expansion alloy, grade 4J32, the molar ratio of its main components is designed to be Fe a Ni b Co c Among them, a=63~65%, b=31~33%, c=3~5%, that is, Fe 63~65 Ni 31~33 Co 3~5 .

[0058] Commercially available low expansion alloys are generally delivered in a forged state. According to YB / T 5241-2014, heat treatment is required to obtain good low expansion properties.

[0059] S1, process the commercially available 4J32 to obtain the standard round bar (φ6mm*25mm) required for thermal expansion test, the disc (φ28mm*3mm) required for XRF test, and the disc (φ20mm*3mm) required for XRD test; S2, for the above test samples, keep them at 840°C for 1 hour and then quench and cool them.

[0060] The thermal expansion coefficient test results of the commercially available ternary Fe-Ni-Co low expansion alloy are shown in Figure 1 ; XRD characterization results are shown in Figure 2 The commercially available 4J32 contains some trace elements such as Mn and Cu to adjust the thermal expansion coefficient at 100°C.

[0061] Comparative Example 3 The basic operation is the same as that of Example 1, except that steps S3 and S5 are not performed.

[0062] Comparative Example 4 The basic operation is the same as that of Example 1, except that step S5 is not performed.

[0063] The XRF impurity semi-quantitative full spectrum scanning results of Examples 1-8 and Comparative Examples 1-4 are shown in Table 1: Table 1 XRF impurity semi-quantitative full spectrum scanning results

[0064] The test results of thermal expansion coefficient of low expansion alloys of Example 1-8 and Comparative Example 1-4 are shown in Table 2: Table 2 Thermal expansion coefficient test results

[0065] Comparative Example 2 is a commercially available ternary Fe-Ni-Co low expansion alloy. In order to remove harmful elements such as O, S, and P in the matrix, it is inevitable to add elements such as Mn and Si to precipitate them from the alloy matrix in the form of compounds. In a relatively low temperature range, it has a certain inhibitory effect on lattice thermal vibration, so it has a relatively low thermal expansion coefficient at 100°C. However, as the temperature increases, the thermal expansion coefficient increases. It can be seen from Table 2 that the thermal expansion coefficient of the low expansion alloy of Examples 1-8 at 20~200°C is significantly lower than that of Comparative Examples 1-4, and its high temperature resistance and low expansion performance are excellent.

[0066] The various aspects, embodiments, and features of the present invention should be considered to be illustrative in all aspects and are not intended to limit the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0067] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0068] Although the present invention has been described with reference to illustrative embodiments, it will be appreciated by those skilled in the art that various other changes, omissions and / or additions may be made and that elements of the described embodiments may be substituted with substantial equivalents without departing from the spirit and scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from the scope of the present invention. Therefore, it is not intended herein to limit the present invention to the specific disclosed embodiments for carrying out the present invention, but rather it is intended that the present invention will include all embodiments within the scope of the appended claims.

Claims

1. A high temperature resistant low expansion alloy, characterized in that: The high temperature resistant low expansion alloy is an FCC single-phase structure; the average thermal expansion coefficient of the high temperature resistant low expansion alloy at 20-200°C is 2×10 -6 / ℃ below.

2. The high temperature resistant low expansion alloy according to claim 1, characterized in that: The high temperature resistant low expansion alloy includes at least any one of a binary Fe-Ni alloy or a ternary Fe-Co-Ni alloy.

3. The high temperature resistant low expansion alloy according to claim 2, characterized in that: The average thermal expansion coefficient of the binary Fe-Ni alloy at 20-200°C is 1.5×10 -6 / ℃ below; And / or, the average thermal expansion coefficient of the ternary Fe-Co-Ni alloy at 20-200°C is within 2×10 -6 / ℃ below; And / or, the average thermal expansion coefficient of the high temperature resistant low expansion alloy at 20-100°C is within 2×10 -6 / ℃ below.

4. The high temperature resistant low expansion alloy according to claim 2, characterized in that: The high temperature resistant low expansion alloy further comprises trace elements which may be selectively added or not added, wherein the trace elements comprise any one or a combination of two or more of Cu, Nb, Ti and Zr; And / or, the content of matrix impurity elements in the high temperature resistant low expansion alloy is less than 100 PPM, and the matrix impurity elements include any one or a combination of two or more of C, S, P, Si, Mn, Al, Cr, and Ca.

5. A method for preparing a high temperature resistant low expansion alloy, characterized in that: include: The raw materials are subjected to cold crucible vacuum suspension melting technology to obtain a master alloy matrix, and then subjected to vacuum high temperature annealing and heat treatment to prepare a high temperature resistant low expansion alloy.

6. The preparation method according to claim 5, characterized in that: include: Raw materials of a binary Fe-Ni alloy or a ternary Fe-Co-Ni alloy are prepared; wherein the mass ratio of Fe to Ni in the binary Fe-Ni alloy is 63-65:35-37; the mass ratio of Co to Ni in the ternary Fe-Co-Ni alloy is 3-5:31-33, and the balance is iron.

7. The preparation method according to claim 5, characterized in that: include: The raw materials are prepared by cold crucible vacuum suspension melting technology to obtain a master alloy matrix; wherein the vacuum degree of the cold crucible vacuum suspension melting technology is less than 1×10 -3 Pa, melting time is 0.2~1h, and refining time is 1~5min.

8. The preparation method according to claim 5, characterized in that: Also includes: The master alloy matrix is ​​less than 1×10 -3 The alloy matrix is ​​homogenized by vacuum high temperature annealing at 1000-1200°C for 5-10 hours.

9. The preparation method according to claim 8, characterized in that: Also includes: The homogenized alloy matrix is ​​heat treated at 800-900° C. for 1-3 hours to prepare a high temperature resistant low expansion alloy.

10. A high temperature resistant low expansion alloy prepared by the preparation method according to any one of claims 5 to 9.

Images