High-stability novel precision resistance alloy and preparation method thereof

Abstract

The invention belongs to the technical field of preparation and processing of high-precision resistance materials, and particularly relates to a high-stability novel precision resistance alloy and a preparation method thereof. In order to solve the problem that in the long-term high-temperature service process of an existing precision resistance Evin alloy, a metastable state strengthening phase in an alloy microstructure can be coarsened, converted or dissolved under long-term thermodynamic driving, and consequently the resistivity is unstable, the following technical scheme is adopted: the novel precision resistance alloy with high stability is prepared; the alloy comprises the following elements in percentage by mass: 19.75%-22.42% of Cr, 2.84%-3.75% of Al, 2.72%-3.24% of Cu, 0.57%-1.87% of Zr and the balance of Ni. The preparation method comprises the following steps: preparing raw materials; smelting and casting to obtain as-cast alloy; forging and cogging; performing four-pass hot rolling after preheating; annealing treatment; carrying out metastable deformation treatment after preheating; gradient cooling; and performing surface degreasing treatment. The prepared novel precision resistance alloy has higher annual stability.

Description

Technical Field

[0001] This invention belongs to the field of high-precision resistive material preparation and processing technology, specifically relating to a novel high-stability precision resistive alloy and its preparation method. Background Technology

[0002] Precision resistance alloys are key basic materials in fields such as instrumentation, sensors, precision measurement, and aerospace. Their core requirements lie in extremely low temperature coefficient of resistance (TCR), high long-term stability (i.e., minimal rate of change in resistance over time), good corrosion resistance, and suitable resistivity. As modern industry develops towards higher precision, higher reliability, and miniaturization, the performance requirements for precision resistance alloys are becoming increasingly stringent.

[0003] Evanohm alloys, as a classic precision resistance alloy, have been widely used in instrumentation, aerospace sensors, precision measurement, and electronic components since their introduction. Their typical composition is based on nickel-chromium, with performance optimized by adding elements such as aluminum and copper. Their core advantages lie in their relatively low temperature coefficient of resistance (TCR) and high resistivity, while maintaining good machinability and long-term service stability. However, with the rapid development of modern industrial technology, especially in aerospace, deep-earth exploration, and high-precision instruments, the performance requirements for precision resistance alloys are becoming increasingly stringent. Under long-term high-temperature (e.g., exceeding 125°C) or high-humidity, high-frequency dynamic load environments, the resistivity of traditional Evanohm alloys is prone to irreversible slight drift. This is because metastable strengthening phases (such as precipitates) in the alloy's microstructure undergo coarsening, transformation, or dissolution under long-term thermodynamic driving, leading to a baseline shift in resistivity and TCR. Although this drift over time is small, it constitutes a performance bottleneck for key components such as high-precision reference resistors and long-term sensor bridge arms.

[0004] Therefore, there is an urgent need to develop a new type of precision resistance alloy with high stability and its preparation method, so as to ensure comprehensive performance, achieve long-term stable microstructure, controllable preparation process and moderate cost, so as to meet the harsh requirements of advanced industrial fields for materials in extreme environments. Summary of the Invention

[0005] The main objective of this invention is to overcome the shortcomings of the prior art and provide a novel high-stability precision resistance alloy and its preparation method, so as to solve the problem that the metastable strengthening phase in the microstructure of the precision resistance Evan alloy will coarsen, transform or dissolve under long-term thermodynamic driving during long-term high-temperature service, resulting in unstable resistivity.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a novel precision resistance alloy with high stability, composed of Ni, Cr, Al, Cu, and Zr, wherein the mass percentages of each element are: Cr 19.75~22.42wt%, Al 2.84~3.75wt%, Cu 2.72~3.24wt%, Zr 0.57-1.87wt%, with the balance being Ni. The mass percentages of each component satisfy the following relationship: Cr(wt%) = 5×Al(wt%) + 2×Cu(wt%) + 1.2×Zr(wt%).

[0007] The preparation method of the novel high-stability precision resistance alloy includes the following steps: S1. Clean the surfaces of Ni, Cr, Al, Cu and Zr components, mix them according to the above mass percentages, perform vacuum melting, and cast to obtain a billet; S2. Forging the billet to open it up; S3. Preheat the billet; S4. Perform four passes of unidirectional hot rolling on the preheated billet to obtain a 4.0-5.0 mm rolled plate; S5. Perform a first annealing on the rolled plate to relieve stress; S6. Preheat the sample obtained in S5; S7. Perform metastable deformation on the preheated sample to obtain a 3.0-4.0 mm strip; S8. Perform gradient cooling treatment on the strip; S9. Perform degreasing and cleaning treatment to obtain precision resistance alloy strip; Furthermore, in S1, the specific method of the melting and casting process is as follows: a certain amount of Ni, Cr, Al, Cu, and Zr are weighed according to the mass percentage ratio and added to a crucible for melting under vacuum conditions, and then cast into an ingot. Furthermore, in S2, the specific method of forging is as follows: the obtained ingot is forged into a billet at a forging temperature of 1000-1100℃.

[0008] Furthermore, in S3, the preheating temperature is 1000-1200℃.

[0009] Furthermore, in S4, the specific method of hot rolling is as follows: the rolled plate is fed into a twin-roll mill for four passes of unidirectional hot rolling, the hot rolling temperature is controlled at 1000-1200℃, and the reduction per pass is 15-25%, to obtain a 4.0-5.0mm hot-rolled slab.

[0010] Furthermore, in step S5, the annealing process is specifically performed as follows: the annealing temperature is 1050-1100℃, and the holding time is 30-60 minutes.

[0011] Furthermore, in S6, the preheating temperature is 500-550℃.

[0012] Furthermore, in S7, the specific method for metastable deformation is as follows: the rolled plate is fed into a twin-roll mill for one pass of unidirectional hot rolling, the hot rolling temperature is controlled at 500-550℃, the reduction is 5-20%, and a 3.0-4.0mm strip is obtained.

[0013] Furthermore, in step S8, the specific method for gradient cooling is as follows: the temperature is increased from 500℃ at a rate of 25℃ / h. Cool down to 300℃, keep warm for 2 hours, and then cool down from 300℃ to 0℃ at a rate of 150℃ / h.

[0014] The beneficial effects of this invention are: This invention provides a novel high-stability precision resistance alloy, which is based on a nickel-chromium precision resistance alloy with the addition of Zr. By adding Zr, the configuration of chromium atom clusters remains unchanged, significantly improving the stability of the metastable strengthening phase, thereby enhancing the annual stability of the precision resistance alloy. In the preparation of a novel precision resistance alloy with high stability, this invention precisely controls the Zr content and introduces metastable deformation to improve the alloy's annual stability. Insufficient Zr content results in insignificant stabilization, while excessive Zr reacts with Al in the matrix, reducing the alloy's cold working plasticity. Introducing metastable deformation—deformation within the temperature range where Cr forms numerous clusters—enhances the Zr stabilization effect, promoting cluster formation and thus improving the alloy's annual stability. Furthermore, the metastable deformed strip undergoes a gradient cooling treatment to further stabilize the cluster structure. Attached Figure Description

[0015] The invention will now be further described with reference to the accompanying drawings.

[0016] Figure 1 This is a flowchart illustrating the preparation process of a novel precision resistance alloy with high stability according to the present invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0018] A novel precision resistance alloy with high stability and its preparation method, comprising the following steps: (1) The surfaces of Ni, Cr, Al, Cu and Zr are cleaned and vacuum-melted according to the following proportions: Cr 21.09wt%, Al 2.95wt%, Cu 2.73wt%, Zr 0.73wt%, with the balance Ni, to obtain a billet. (2) Forging the billet at 1000℃ to open the blank; (3) Preheat the billet to 1150℃; (4) The preheated billet is subjected to 4 passes of unidirectional hot rolling, specifically the hot rolling temperature is controlled at 1150℃ and the reduction in each pass is 15%, to obtain a 4.5mm rolled plate; (5) The rolled plate is annealed once at a temperature of 1000℃ and a holding time of 60min to relieve stress; (6) Preheat the sample obtained in S5 to 500℃; (7) Metastable deformation was performed on the preheated sample. Specifically, the plate was fed into a twin-roll mill for one pass of unidirectional hot rolling. The hot rolling temperature was controlled at 500℃ and the reduction was 15% to obtain a 3.8mm strip. (8) The strip is subjected to gradient cooling treatment, specifically: the temperature is reduced from 500℃ to 300℃ at a rate of 25℃ / h, kept at the temperature for 2h, and then the temperature is reduced from 300℃ to 0℃ at a rate of 150℃ / h. (9) Degreasing and cleaning treatment is performed to obtain precision resistance alloy strip; The finished strip prepared in Example 1 was subjected to an annual stability test. The strip was kept at 200°C for 100 hours, and the change in resistance was measured. The experimentally measured change in resistance was 0.52%, which meets the usage requirements. Example 2

[0019] A novel precision resistance alloy with high stability and its preparation method, comprising the following steps: (1) The surfaces of Ni, Cr, Al, Cu and Zr were cleaned and vacuum-melted according to the following proportions: Cr 22.42wt%, Al 2.84wt%, Cu 3.21wt%, Zr 1.5wt%, with the balance Ni, to obtain a casting billet. (2) Forging the billet at 1050℃; (3) Preheat the billet to 1000℃; (4) The preheated billet is subjected to 4 passes of unidirectional hot rolling, specifically the hot rolling temperature is controlled at 1000℃ and the reduction in each pass is 20%, to obtain a 4.2mm rolled plate; (5) The rolled plate is annealed once at a temperature of 1100℃ and a holding time of 30min to relieve stress; (6) Preheat the sample obtained in S5 to 550℃; (7) Metastable deformation was performed on the preheated sample. Specifically, the plate was fed into a twin-roll mill for one pass of unidirectional hot rolling. The hot rolling temperature was controlled at 550°C and the reduction was 10% to obtain a 3.7mm strip. (8) The strip is subjected to gradient cooling treatment, specifically: the temperature is reduced from 500℃ to 300℃ at a rate of 25℃ / h, kept at the temperature for 2h, and then the temperature is reduced from 300℃ to 0℃ at a rate of 150℃ / h. (9) Degreasing and cleaning treatment is performed to obtain precision resistance alloy strip; The finished strip prepared in Example 2 was subjected to an annual stability test. The strip was kept at 200°C for 100 hours, and the change in resistance was measured. The experimentally measured change in resistance was 0.56%, which meets the usage requirements. Example 3

[0020] A novel precision resistance alloy with high stability and its preparation method, comprising the following steps: (1) The surfaces of Ni, Cr, Al, Cu and Zr were cleaned and vacuum-melted according to the following proportions: Cr 22.42wt%, Al 3.12wt%, Cu 2.84wt%, Zr 0.95wt%, with the balance Ni, to obtain a casting billet. (2) Forging the billet at 1050℃; (3) Preheat the billet to 1200℃; (4) The preheated billet is subjected to 4 passes of unidirectional hot rolling, specifically the hot rolling temperature is controlled at 1200℃ and the reduction in each pass is 25%, to obtain a 4.0mm rolled plate; (5) The rolled plate is annealed once at a temperature of 1050℃ and a holding time of 40min to relieve stress; (6) Preheat the sample obtained in S5 to 520℃; (7) Metastable deformation was performed on the preheated sample. Specifically, the plate was fed into a twin-roll mill for one pass of unidirectional hot rolling. The hot rolling temperature was controlled at 520°C and the reduction was 5% to obtain a 3.8mm strip. (8) The strip is subjected to gradient cooling treatment, specifically: the temperature is reduced from 500℃ to 300℃ at a rate of 25℃ / h, kept at the temperature for 2h, and then the temperature is reduced from 300℃ to 0℃ at a rate of 150℃ / h. (9) Degreasing and cleaning treatment is performed to obtain precision resistance alloy strip; The finished strip prepared in Example 3 was subjected to an annual stability test. The strip was kept at 200°C for 100 hours, and the change in resistance was measured. The experimentally measured change in resistance was 0.51%, which meets the usage requirements.

[0021] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the Zr content in the alloy composition is reduced to 0, while other contents and the preparation process remain unchanged. The process is as follows: S1. Prepare raw materials according to the required composition and proportion, perform surface treatment, vacuum melt, and cast to obtain a billet; S2. Forging the billet to open it up; S3. Preheat the billet; S4. The preheated billet is subjected to four passes of unidirectional hot rolling to obtain the rolled plate; S5. Perform a first annealing on the rolled plate to relieve stress; S6. Preheat the sample obtained in S5; S7. Perform metastable deformation on the preheated sample to obtain the strip; S8. After rolling, the strip is subjected to gradient cooling treatment; S9. Perform degreasing and cleaning treatment to obtain a precision resistance alloy sample.

[0022] The samples were subjected to an annual stability test by maintaining them at 200℃ for 100 hours and measuring the change in resistance. The measured change in resistance was 1.2%.

[0023] The experimental results show that, compared to Example 1, the material after Zr removal exhibits a significantly increased resistance change and decreased annual stability after 100 hours of holding at 200℃. The main reason is the lack of Zr reinforcement on the metastable strengthening phase (Cr atom clusters), which reduces the stability of the metastable strengthening phase and makes it more susceptible to transformation into other phases during subsequent processing, leading to a substantial increase in the material's resistance change and decreased annual stability.

[0024] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that metastable deformation is not performed when preparing the novel high-stability precision resistance alloy, while other contents and preparation processes remain unchanged. The process is as follows: S1. Prepare raw materials according to the required composition and proportion, perform surface treatment, vacuum melt, and cast to obtain a billet; S2. Forging the billet to open it up; S3. Preheat the billet; S4. The preheated billet is subjected to four passes of unidirectional hot rolling to obtain the rolled plate; S5. Perform a first annealing on the rolled plate to relieve stress; S6. Preheat the sample obtained in S5; S7. Perform gradient cooling on the sample after preheating in S6; S8. Perform degreasing and cleaning treatment to obtain a precision resistance alloy sample.

[0025] The samples were subjected to an annual stability test by maintaining them at 200℃ for 100 hours and measuring the change in resistance. The measured change in resistance was 0.92%.

[0026] The experimental results show that, compared to Example 1, the material without metastable deformation exhibits a significantly increased change in electrical resistance and a decreased annual stability after being held at 200°C for 100 hours. The main reason is that without metastable deformation, the content of spontaneously formed metastable reinforcing phases in the material is limited, and the reduced content of metastable reinforcing phases leads to a substantial increase in the change in electrical resistance and a decrease in annual stability.

[0027] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that, in preparing the novel high-stability precision resistance alloy, the preheating temperature in S6 is increased by 200°C, while other contents and preparation processes remain unchanged. The process is as follows: S1. Prepare raw materials according to the required composition and proportion, perform surface treatment, vacuum melt, and cast to obtain a billet; S2. Forging the billet to open it up; S3. Preheat the billet; S4. The preheated billet is subjected to four passes of unidirectional hot rolling to obtain the rolled plate; S5. Perform a first annealing on the rolled plate to relieve stress; S6. Preheat the sample obtained in S5; S7. Perform metastable deformation on the preheated sample to obtain the strip; S8. Perform gradient cooling on the preheated sample; S9. Perform degreasing and cleaning treatment to obtain a precision resistance alloy sample.

[0028] The samples were subjected to an annual stability test by maintaining them at 200℃ for 100 hours and measuring the change in resistance. The measured change in resistance was 3.68%.

[0029] The experimental results show that, compared to Example 1, the preheating temperature in S6 increased by 200°C. The material was held at 200°C for 100 hours, resulting in a significant increase in resistance change and a decrease in annual stability. The main reason is that the increased preheating temperature prevents chromium from forming clusters and thus hinders the formation of metastable reinforcing phases. Instead, it leads to the formation of numerous coarse precipitates, preventing the material from exhibiting the precise characteristics of a precision resistor, resulting in a substantial increase in resistance change and a decrease in annual stability.

[0030] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the preheating temperature in S6 is reduced by 150°C when preparing the novel high-stability precision resistance alloy, while other contents and preparation processes remain unchanged. The process is as follows: S1. Prepare raw materials according to the required composition and proportion, perform surface treatment, vacuum melt, and cast to obtain a billet; S2. Forging the billet to open it up; S3. Preheat the billet; S4. The preheated billet is subjected to four passes of unidirectional hot rolling to obtain the rolled plate; S5. Perform a first annealing on the rolled plate to relieve stress; S6. Preheat the sample obtained in S5; S7. Perform metastable deformation on the preheated sample to obtain the strip; S8. Perform gradient cooling on the preheated sample; S9. Perform degreasing and cleaning treatment to obtain a precision resistance alloy sample.

[0031] The samples were subjected to an annual stability test by maintaining them at 200℃ for 100 hours and measuring the change in resistance. The measured change in resistance was 2.56%.

[0032] The experimental results show that, compared to Example 1, the preheating temperature in S6 was reduced by 150°C, and the material was held at 200°C for 100 hours. The resulting change in electrical resistance significantly increased, and the annual stability decreased. The main reason is that the lower preheating temperature prevents chromium from diffusing to form stable chromium atom clusters. This means the metastable strengthening phase becomes less stable and is more likely to transform into other phases during subsequent processing, leading to a significant increase in the material's electrical resistance and reduced annual stability.

[0033] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that gradient cooling was not performed when preparing the novel high-stability precision resistance alloy, while other contents and preparation processes remained unchanged. The process is as follows: S1. Prepare raw materials according to the required composition and proportion, perform surface treatment, vacuum melt, and cast to obtain a billet; S2. Forging the billet to open it up; S3. Preheat the billet; S4. The preheated billet is subjected to four passes of unidirectional hot rolling to obtain the rolled plate; S5. Perform a first annealing on the rolled plate to relieve stress; S6. Preheat the sample obtained in S5; S7. Perform metastable deformation on the preheated sample to obtain the strip; S8. Rapidly cool the preheated sample; S9. Perform degreasing and cleaning treatment to obtain a precision resistance alloy sample.

[0034] The samples were subjected to an annual stability test by maintaining them at 200℃ for 100 hours and measuring the change in resistance. The measured change in resistance was 1.96%.

[0035] The experimental results show that, compared to Example 1, without gradient cooling in S8, the material exhibits a significantly increased resistance change and decreased annual stability after being held at 200℃ for 100 hours. The main reason is the accelerated cooling rate, which prevents further stabilization of the cluster structure through slow cooling, resulting in a substantial increase in the material's resistance change and reduced annual stability.

[0036] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A novel precision resistance alloy with high stability, characterized in that, It contains the following raw materials by mass percentage: Cr 19.75~22.42wt%, Al 2.84~3.75wt%, Cu 2.72~3.24wt%, Zr 0.57-1.87wt%, with the balance being Ni.

2. The novel high-stability precision resistance alloy according to claim 1, characterized in that, The mass percentages of Cr, Al, Cu, and Zr in the raw materials satisfy the following relationship: Cr (wt%) = 5 × Al (wt%) + 2 × Cu (wt%) + 1.2 × Zr (wt%).

3. The method for preparing a novel high-stability precision resistance alloy according to claim 1, characterized in that, Includes the following steps: S1. Clean the surfaces of Ni, Cr, Al, Cu and Zr components, mix them according to the above mass percentages, perform vacuum melting, and cast to obtain a billet; S2. Forging the billet to open it up; S3. Preheat the billet; S4. The preheated billet is subjected to four passes of unidirectional hot rolling to obtain the rolled plate; S5. Perform a first annealing on the rolled plate to relieve stress; S6. Preheat the sample obtained in S5; S7. Perform metastable deformation on the preheated sample to obtain the strip; S8. After rolling, the strip is subjected to gradient cooling treatment; S9. Perform degreasing and cleaning treatment to obtain precision resistance alloy strip.

4. The method for preparing a novel high-stability precision resistance alloy according to claim 3, characterized in that, The specific method of forging in S2 is as follows: the obtained ingot is forged into a blank, and the forging temperature is 1000-1100℃.

5. The method for preparing a novel high-stability precision resistance alloy according to claim 3, characterized in that, The specific method of hot rolling in S4 is as follows: the rolled plate is fed into a twin-roll mill for four passes of unidirectional hot rolling, the hot rolling temperature is controlled at 1000-1200℃, and the reduction in each pass is 15-25%, to obtain a 4.0-5.0mm hot-rolled slab.

6. The method for preparing a novel high-stability precision resistance alloy according to claim 3, characterized in that, The specific method for annealing in S5 is as follows: the annealing temperature is 1050-1100℃, and the holding time is 30-60min.

7. The method for preparing a novel high-stability precision resistance alloy according to claim 3, characterized in that, The specific method for metastable deformation in S7 is as follows: the rolled plate is fed into a twin-roll mill for one pass of unidirectional hot rolling, the hot rolling temperature is controlled at 500-550℃, the reduction is 5-20%, and a 3.0-4.0mm hot-rolled strip is obtained.

8. The method for preparing a novel high-stability precision resistance alloy according to claim 3, characterized in that, The specific method of gradient cooling in S8 is as follows: the temperature is reduced from 500℃ to 300℃ at a rate of 25℃ / h, held for 2h, and then the temperature is reduced from 300℃ to 0℃ at a rate of 150℃ / h.

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