Negative temperature coefficient copper-manganese-silicon alloy for precision resistors and method for producing same

Abstract

This invention relates to a negative temperature coefficient copper-manganese-silicon alloy for precision resistors and its preparation method. The alloy composition comprises, by mass percentage: Mn 10.00%–12.00%, Si 0.70%–1.00%, Sn 0.10%–0.25%, Re 0.10%–0.20%, with the balance being Cu. The alloy has a grain size of 10–100 μm, a resistivity of 0.40–0.50 μΩ·m, and an average temperature coefficient of resistance of -50 to -10 ppm / ℃ at 20–60℃; and an average temperature coefficient of resistance of -100 to -60 ppm / ℃ at 20–120℃. The preparation process includes vacuum melting, hot forging, homogenization annealing, multi-pass rolling, and recrystallization annealing. The microstructure and properties are controlled by a protective atmosphere and segmented cooling, making it suitable for preparing precision resistance alloy resistor elements operating over a wide temperature range.

Description

Technical Field

[0001] This invention relates to the field of resistance alloy materials, specifically to a negative temperature coefficient copper-manganese-silicon alloy for precision resistors and its preparation method. Background Technology

[0002] Manganese-copper alloys, due to their excellent machinability and stable electrical properties, have become the core basic materials in the field of precision resistors, and are widely used in the manufacture of resistive elements, testing instruments, and industrial control equipment. Manganese-copper alloys use copper (Cu) and manganese (Mn) as the main matrix elements, and alloying elements such as nickel (Ni) and tin (Sn) can be added in appropriate amounts during the smelting process to optimize the overall performance according to performance requirements. Among them, the Cu-12%Mn-4%Ni alloy (commonly known as "manganese-nitrogen alloy," corresponding to national standard grades 6J12 and 6J13) has remained one of the most widely used alloy materials in the field of precision resistor alloys since the 19th century, thanks to its low temperature coefficient of resistance, good long-term resistance stability, and excellent machinability.

[0003] With the rapid development of emerging fields such as high-speed rail, aerospace, new energy vehicles, and industrial robots, the market demand for precision resistance alloys continues to grow. Furthermore, the application environments are becoming increasingly complex and demanding, placing stringent requirements on the electrical properties of resistance alloy materials, including wide temperature range applicability, negative temperature coefficient of resistance, low resistance drift, and high stability. If these performance requirements are not met, resistance alloy materials are prone to failure problems such as oxidation corrosion, thermal fatigue, and resistance drift during use, making it difficult to guarantee the long-term reliable operation of devices.

[0004] Taking new energy vehicles as an example, the operating temperature range of shunt resistors covers "20~120℃", the operating current span is large and the short-term inrush current is extremely high. In order to reduce temperature rise and energy consumption, the resistance alloy material is required to have a lower resistance temperature coefficient and higher detection accuracy.

[0005] However, traditional manganese-copper alloys, such as 6J12 and 6J13, can only achieve a temperature coefficient of resistance of -20 to +20 ppm / ℃ within a narrow temperature range of 20–60℃. In a wider temperature range of 20–120℃, the average temperature coefficient of resistance for the 6J12 alloy is only -50 to -20 ppm / ℃, which cannot meet the requirements for high-precision detection over a wide temperature range. Furthermore, the ΔR / RT curve of this alloy is parabolic, maintaining a low temperature coefficient of resistance only near the peak of the narrow temperature range, resulting in poor resistance stability over a wider temperature range.

[0006] To improve the temperature coefficient of resistance over a wide temperature range, those skilled in the art have attempted to add Si to Cu-12%Mn-4%Ni alloys. While this can control the temperature coefficient of resistance to some extent, it leads to a significant decrease in alloy plasticity and an increase in brittleness. This exacerbates the tendency to crack during cold working, significantly increases processing difficulty and the defect rate of finished products, and raises the risk of shunt resistor failure. Furthermore, traditional manganese-copper alloys contain 2–4% Ni, which is a strategic metal mineral with a higher price than Cu, Mn, and Si. Therefore, large-scale production would significantly increase material preparation costs, making it difficult to meet the demands of low-cost, large-scale applications.

[0007] To address the aforementioned issues of poor wide-temperature adaptability, high temperature coefficient of resistance, deteriorated processing performance, and high manufacturing cost, those skilled in the art have proposed several improvement schemes, but they have still failed to achieve synergistic optimization of the performance, processing performance, and cost of resistance alloy materials.

[0008] For example, the patent document CN117626049A, entitled "Copper-Manganese Alloy Material and Manufacturing Method Thereof", reduces the cost of the alloy by partially replacing the expensive Ge element with Si. The prepared alloy can have a temperature coefficient of resistance of 0 to 10 ppm / ℃ in a wide temperature range of -20 to 120℃. However, it cannot achieve a stable negative temperature coefficient of resistance in a wide temperature range, which makes it difficult to effectively compensate with the positive temperature coefficient of the copper electrode. In addition, it still retains 2% to 5% Ni element, so the space for cost optimization is limited.

[0009] For example, patent document CN115537597B, entitled "A Manganese-Copper Alloy with Negative Temperature Coefficient of Resistance, Preparation Method and Applications," describes an alloy based on the classic Cu-Mn-Ni manganese-copper alloy. By adding various elements such as V, Sn, Si, Fe, and rare earth elements, it achieves a negative temperature coefficient of resistance of -100 to -60 ppm / °C over a wide temperature range of -20 to 120°C. However, in practical applications, those skilled in the art have found that this method requires the addition of multiple rare metals and rare earth elements, resulting in high raw material costs. Furthermore, the preparation process is difficult to control and consumes a lot of energy, which is not conducive to large-scale production.

[0010] While the two existing patented technologies mentioned above can achieve some improvements in terms of wide-temperature performance, processability, or cost, they both contain Ni, Fe, and Si elements. In actual smelting and heat treatment processes, those skilled in the art have found that Fe and Ni easily combine with Si to form intermetallic precipitates. These precipitates, which agglomerate at grain boundaries, significantly reduce the plasticity of the alloy material, increase the risk of processing cracks, and at the same time destroy the electrical stability of the alloy material, leading to problems such as temperature coefficient of resistance drift and fluctuations in the thermoelectric potential of copper. They cannot fundamentally meet the requirements for the use of high-reliability, high-stability precision resistance alloys.

[0011] In summary, existing manganese-copper precision resistance alloys cannot simultaneously meet the requirements of wide temperature range adaptability, low temperature coefficient of resistance, excellent processing and forming performance, and low cost for industrial applications. Developing a new type of precision resistance alloy with a negative temperature coefficient and better overall performance has become an urgent technical problem to be solved in this field. Summary of the Invention

[0012] This invention addresses the shortcomings of existing technologies by providing a negative temperature coefficient copper-manganese-silicon alloy for precision resistors and its preparation method. The copper-manganese-silicon alloy has a grain size of 10–100 μm, a resistivity of 0.40–0.50 μΩ·m, an average temperature coefficient of resistance of -50–-10 ppm / ℃ at 20–60℃, and an average temperature coefficient of resistance of -100–-60 ppm / ℃ at 20–120℃. It is suitable for preparing precision resistor alloy resistor elements under wide temperature range conditions.

[0013] The objective of this invention is achieved through the following approach:

[0014] A negative temperature coefficient copper-manganese-silicon alloy for precision resistors is disclosed. The mass percentage of each component in the copper-manganese-silicon alloy is as follows: Mn 10.0%–12.0%, Si 0.7%–1.0%, Sn 0.10%–0.25%, Re 0.10%–0.20%, with the balance being Cu. The copper-manganese-silicon alloy has a grain size of 10–100 μm, a resistivity of 0.4–0.5 μΩ·m, an average temperature coefficient of resistance of -50 to -10 ppm / ℃ at 20–60℃, and an average temperature coefficient of resistance of -100 to -60 ppm / ℃ at 20–120℃.

[0015] A method for preparing a negative temperature coefficient copper-manganese-silicon alloy as described above includes the following steps:

[0016] 1) Vacuum melting

[0017] The components are taken according to the proportions of the alloy described in claim 1, and after vacuum melting and casting, an ingot is obtained;

[0018] 2) Hot forging and homogenization annealing

[0019] The ingot is hot forged to obtain a slab; the slab is then subjected to homogenization annealing to obtain a slab after homogenization annealing.

[0020] 3) Initial roughing and first recrystallization annealing

[0021] The slab after homogenization annealing is rolled to obtain a sheet; the sheet is then subjected to a first recrystallization annealing treatment to obtain a sheet after the first recrystallization annealing treatment.

[0022] 4) Cold rolling and second recrystallization annealing

[0023] The sheet metal after the first recrystallization annealing treatment is cold rolled to obtain a rough-rolled strip billet; the rough-rolled strip billet is then subjected to a second recrystallization annealing treatment to obtain a rough-rolled strip billet after the second recrystallization annealing treatment, in order to control the alloy grain size and ensure that the finished product grain size meets the requirements.

[0024] 5) Finished product rolling and finished product recrystallization annealing

[0025] The rough-rolled strip billet after the second recrystallization annealing treatment is cold-rolled to obtain the finished strip billet; the finished strip billet is then subjected to finished recrystallization annealing treatment to obtain the negative temperature coefficient copper-manganese-silicon alloy finished strip.

[0026] Preferably, in step 1), the vacuum degree of the melting process is <100 Pa.

[0027] Preferably, the hot forging temperature is 600–850°C, the homogenization annealing temperature is 680–780°C, the holding time is 5–10 hours, and the temperature is rapidly cooled.

[0028] Preferably, in step 3), the first recrystallization annealing treatment is performed as follows: under a nitrogen protective atmosphere, the annealing temperature is 650-750°C, the holding time is 4.5-6.5 hours, and then rapid cooling is performed.

[0029] Preferably, in step 4), the second recrystallization annealing treatment is performed as follows: under a protective atmosphere of ammonia decomposition gas, the annealing temperature is 650-850℃, the holding time is 2-20 minutes, and then air-cooled.

[0030] Preferably, in step 5), the recrystallization annealing treatment of the finished product is carried out under the protective atmosphere of ammonia decomposition gas, with an annealing temperature of 650-800℃, a holding time of 1-10 min, and air cooling.

[0031] Application of a negative temperature coefficient copper-manganese-silicon alloy in the manufacture of precision resistance alloy elements for wide temperature range operating conditions.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. This invention uses Cu as the matrix and achieves a precise balance between a wide-temperature-range negative temperature coefficient, excellent processing performance, long-term service stability, and low cost through the synergistic effect of functional additives such as Mn, Si, Sn, and Re.

[0034] 1-1) Mn (10.00%–12.00%) and Si (0.70%–1.00%) are the main functional elements, with Mn forming the basis of the electrical properties of copper-manganese-silicon alloys, and Si refining the grain size. Simultaneously, Si can form intermetallic compounds such as Mn5Si3 and Cu3Si with Cu and Mn, increasing grain boundaries and crystal defects, significantly enhancing the electron scattering effect. This scattering effect dominates the change in resistivity with increasing temperature, ultimately leading to a decrease in resistivity with increasing temperature, thus giving the copper-manganese-silicon alloy a stable negative temperature coefficient. Furthermore, the intermetallic compounds such as Mn5Si3 and Cu3Si formed by Si with Cu and Mn can block atomic migration at high temperatures, improving the thermal stability of the material and preventing significant resistivity drift.

[0035] 1-2) The Si content in the copper-manganese-silicon alloy of the present invention is 0.50% to 1.00%, which is relatively high compared with the conventional manganese-copper alloy. This would have an adverse effect on the plasticity of the material. However, the present invention has made targeted optimization by adding Sn (0.10% to 0.50%) as a plasticity improving element: Sn can be dissolved in the copper matrix, which can alleviate the matrix brittleness problem caused by Si in the alloy, thereby improving the cold working performance of the copper-manganese-silicon alloy, effectively avoiding defects such as cracking and brittle fracture during rolling, and ensuring the feasibility of industrial mass production.

[0036] 1-3) Rare earth element Re (0.1%–0.20%) acts as a stability-enhancing element, further refining the grain size and improving the alloy's plasticity. Simultaneously, it enhances the long-term stability of the alloy's resistance, significantly extending the service life of precision resistive components. Furthermore, rare earth elements can react with impurity elements such as O and S, reducing impurities in the alloy, increasing its purity, and positively impacting electrical and mechanical properties, thus ensuring stable alloy performance. At the same time, this invention strictly controls the amount of rare earth element Re used, avoiding excessively high raw material costs while ensuring performance.

[0037] In summary, this invention completely eliminates the addition of Ni and Fe elements in traditional alloys, thus avoiding the common industry problem of Fe, Ni, and Si forming grain boundary precipitates and degrading the plasticity and electrical stability of the alloy from the compositional source. This invention achieves autonomous regulation of alloy material properties through the synergistic ratio and precise content control of functional elements such as Mn, Si, Sn, and Re. Meanwhile, the preparation process of this invention does not require expensive specialized equipment such as high vacuum and rapid quenching. The process is simple, highly controllable, and suitable for large-scale production. The overall cost is significantly lower than that of conventional precision resistance alloys containing Ni and Fe. Ultimately, the grain size of the copper-manganese-silicon alloy prepared by this invention is stabilized at 10-100 μm, taking into account both excellent processing performance and electrical performance stability. The resistivity reaches 0.4-0.5 μΩ·m, and the average temperature coefficient of resistance is -50 to -10 ppm / ℃ at 20-60℃ and -100 to -60 ppm / ℃ at 20-120℃, which can meet the working conditions of wide temperature range, high precision, and high reliability precision resistance elements.

[0038] 2. The preparation process described in this invention is stable and controllable, ensuring batch-to-batch consistency of the product.

[0039] 2-1) In the smelting process, this application uses a vacuum environment with a vacuum degree of <100Pa to smelt and cast the alloy materials, which can effectively isolate the reaction between impurities in the air and alloy elements, avoid defects such as component segregation and inclusions in the ingot, and ensure that the ingot composition is uniform and the purity meets the standards, thus laying the foundation for the performance stability of subsequent processes from the source.

[0040] 2-2) In the hot forging and homogenization annealing process, this application strictly controls the hot forging temperature at 600-850℃ to ensure the plasticity of the ingot and achieve uniform forming of the billet. The hot-forged billet is then subjected to homogenization annealing at 680-780℃ for 5-10 hours, which can eliminate the internal stress generated by hot forging, make the alloy structure more uniform, and at the same time, the uniform alloy structure is fixed by rapid cooling (immediate oil cooling or immediate water cooling can be used), avoiding coarse grains, and finally obtaining a slab with stable performance.

[0041] 2-3) In the billet rolling and first recrystallization annealing processes, this application achieves gradual reduction of slab thickness and preliminary refinement of alloy microstructure by rolling the billet. After billet rolling, a first recrystallization annealing is performed at 650–750°C for 4.5–6.5 hours under a nitrogen protective atmosphere. The nitrogen atmosphere effectively prevents oxidation of the alloy surface and completely eliminates work hardening caused by billet rolling during the annealing process. Finally, rapid cooling locks in the refined alloy microstructure, ultimately ensuring the uniformity of the plate microstructure and the consistency of its processing performance.

[0042] 2-4) In the cold rolling and second recrystallization annealing process, this application further thins the sheet to a strip shape by cold rolling. After cold rolling, a second recrystallization annealing is performed at 650–850°C for 2–20 minutes under an ammonia decomposition gas protective atmosphere. The ammonia decomposition gas prevents strip oxidation and ensures the stability of the annealing environment. The short holding time of 2–20 minutes achieves recrystallization to refine the grains while avoiding grain growth due to over-annealing. After annealing, air cooling is used to adapt to the characteristics of the thin strip and avoid stress concentration caused by rapid cooling, ultimately ensuring the dimensional accuracy and microstructure uniformity of the strip billet.

[0043] 2-5) In the finished product rolling and finished product recrystallization annealing process, this application achieves precise control of the final thickness of the finished product by performing finished product cold rolling on the strip billet. After cold rolling, finished product recrystallization annealing is carried out at 650-800℃ for 1-10 minutes under the protective atmosphere of ammonia decomposition gas. The short annealing time of 1-10 minutes can further eliminate the internal stress generated during the finished product rolling process, and further optimize the mechanical and electrical properties stability of the strip. After air cooling, it is finally ensured that the finished strip is free from deformation and cracks.

[0044] Through the above-mentioned negative temperature coefficient copper-manganese-silicon alloy preparation process design of the present invention, the parameters of each process are coordinated and progressively improved, and the alloy grain size can be precisely controlled within the optimal range of 10 to 100 μm. This ensures that the core performance parameters such as resistivity and temperature coefficient of resistance of different batches of products fluctuate very little, and the batch consistency is excellent, which fully meets the stringent requirements of industrial mass production for product stability and reliability. Attached Figure Description

[0045] Figure 1 This is a flowchart of the preparation method of the copper-manganese-silicon alloy of the present invention;

[0046] Figure 2 The copper-manganese-silicon alloy of the present invention R / RT curve. Detailed Implementation

[0047] The specific embodiments of the present invention will be described in detail below.

[0048] Example 1

[0049] A copper-manganese-silicon alloy for precision resistors, wherein the mass percentage of each component is: Mn 11.50%, Si 0.75%, Sn 0.20%, Fe 0.20%, Re 0.10%, and the balance is Cu.

[0050] like Figure 1 As shown, the preparation method of this alloy includes the following steps:

[0051] (1) Smelting

[0052] Weigh each raw material according to the above component mass percentage, place the raw materials in a vacuum melting furnace, and melt them under a vacuum degree <100Pa. After melting, pour the molten alloy into a steel ingot mold, and obtain an ingot after cooling.

[0053] (2) Hot forging and homogenization annealing

[0054] The ingot is placed in a forging press and forged into a slab with a thickness of 50 mm at a temperature of 600-850℃. Then, the slab is placed in an annealing furnace and homogenized at a temperature of 750℃ for 420 min. After the annealing is completed, it is immediately water-cooled to room temperature.

[0055] (3) Blanking and first recrystallization annealing

[0056] The slab after homogenization annealing is rolled into a plate with a thickness of 4mm.

[0057] Subsequently, the plate was placed in a pit furnace and subjected to the first recrystallization annealing treatment under a nitrogen protective atmosphere. The annealing temperature was 720℃ and the holding time was 300min. After the annealing treatment was completed, it was immediately water-cooled to room temperature.

[0058] (4) Cold rolling and second recrystallization annealing

[0059] The sheet material after the first recrystallization annealing treatment was cold rolled into a strip billet with a thickness of 1.5 mm. Then, the strip billet was placed in a continuous heat treatment furnace and subjected to a second recrystallization annealing treatment under the protective atmosphere of ammonia decomposition gas. The annealing temperature was 800℃ and the furnace dwell time was 3.5 min. After annealing, it was naturally air-cooled to room temperature.

[0060] (5) Finished product rolling and finished product recrystallization annealing

[0061] The strip billet after the second recrystallization annealing treatment is cold rolled into a finished strip with a thickness of 0.5 mm. Then, the finished strip is placed in a continuous heat treatment furnace and recrystallized under the protective atmosphere of ammonia decomposition gas. The annealing temperature is 720℃ and the furnace dwell time is 2.5 min. After annealing, it is naturally air-cooled to room temperature to obtain the copper manganese silicon alloy finished strip.

[0062] Example 2

[0063] A copper-manganese-silicon alloy for precision resistors, wherein the mass percentage of each component is: Mn 11.20%, Si 0.85%, Sn 0.10%, Fe 0.20%, Re 0.10%, and the balance is Cu.

[0064] The preparation method of the copper-manganese-silicon alloy for precision resistors described in Example 2 is exactly the same as that in Example 1.

[0065] Comparative Example

[0066] A copper-manganese-silicon alloy for precision resistors, wherein the mass percentage of each component is: Mn 12.00%, Si 0.60%, Sn 0.30%, Fe 0.20%, Ni 0.20%, Re 0.10%, and the balance is Cu.

[0067] The preparation method of the copper-manganese-silicon alloy for precision resistors described in the comparative example is exactly the same as that in Example 1.

[0068] The electrical properties of the copper-manganese-silicon alloy strips prepared in Examples 1-2 and the comparative examples were tested. The test methods and results are as follows:

[0069] 1. Electrical performance testing methods

[0070] 1-1 Resistivity Test

[0071] The resistivity was tested using the bridge method, in accordance with the national standard GB / T 6146 "Test Method for Resistivity of Precision Resistance Alloys";

[0072] 1-2 Average Resistance Temperature Coefficient Test

[0073] The average temperature coefficient of resistance was tested using the potentiometer method, in accordance with the national standard GB / T 6148 "Test Method for Temperature Coefficient of Resistance of Precision Resistance Alloys", with test temperature ranges of 20~60℃ and 20~120℃ respectively.

[0074] 2. Electrical performance test results

[0075] The electrical performance test results of the copper-manganese-silicon alloy strips prepared in Examples 1-2 and Comparative Examples are shown in the table below:

[0076] Table 1

[0077]

[0078] As can be seen from the above test results, the copper-manganese-silicon alloys prepared in Examples 1-2 and the comparative examples of the present invention have a resistivity that is stably maintained in the range of 0.4 to 0.5 μΩ·m, an average temperature coefficient of resistance of -50 to -10 ppm / ℃ at 20 to 60℃, and an average temperature coefficient of resistance of -100 to -60 ppm / ℃ at 20 to 120℃, which meets the requirements for use as precision resistance alloys.

[0079] For precision resistance alloy devices, the overall resistance value can be precisely controlled through targeted design of dimensions and structural parameters. The resistivity of the alloy substrate only needs to match the predetermined design range to meet basic application requirements. Currently, resistive elements made of manganese-copper alloy typically require subsequent finishing processes such as splicing and welding, and surface electroplating during actual production. These processes often affect the microstructure of the alloy, causing the temperature coefficient of resistance (TCR) of the finished element to shift positively by 30–100 ppm / ℃ compared to the manganese-copper alloy substrate. However, the copper-manganese-silicon alloy substrate obtained in this invention has a negative TCR, which can effectively compensate for the positive TCR shift caused by subsequent processing processes such as splicing, welding, and electroplating. Through a design mechanism that cancels out the positive and negative coefficients, the TCR of the finished resistive element can be stably controlled to around 0 ppm / ℃, effectively improving the element's temperature drift characteristics and significantly enhancing the temperature stability and measurement accuracy of precision resistive elements, thereby meeting the stringent requirements of precision measurement and control, high-precision metrology, and other demanding operating conditions.

[0080] As shown in Table 1, the temperature coefficient of resistance of the comparative example is higher than that of Examples 1-2, indicating that the electrical stability of the comparative example alloy is worse over a wide temperature range; while the temperature coefficient of resistance of Examples 1-2 is lower, showing better negative temperature coefficient characteristics and wide temperature range stability.

[0081] like Figure 2 As shown, the resistivity change rate of the copper-manganese-silicon alloy described in this invention ( The relationship curve between R / R and temperature (T) shows that the curve consistently exhibits a stable negative slope across a wide temperature range from room temperature to 120°C, without any abnormal fluctuations. This characteristic directly confirms that the copper-manganese-silicon alloy described in this invention maintains a stable temperature coefficient of resistance within the aforementioned wide temperature range, and its resistivity decreases regularly with increasing temperature, without abrupt changes or drift. This further demonstrates that the copper-manganese-silicon alloy described in this invention possesses excellent and stable electrical properties across a wide temperature range, meeting the requirements for electrical performance stability of precision resistance alloy resistor elements under wide temperature range conditions. It can be stably applied for long-term use in the preparation and use of precision resistance alloy resistor elements under wide temperature range conditions.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A negative temperature coefficient copper-manganese-silicon alloy for precision resistors, characterized in that, The mass percentages of the components in the copper-manganese-silicon alloy are as follows: Mn 10.00%–12.00%, Si 0.70%–1.00%, Sn 0.10%–0.25%, Re 0.10%–0.20%, with the balance being Cu. The grain size of this copper-manganese-silicon alloy is 10–100 μm, the resistivity is 0.40–0.50 μΩ·m, the average temperature coefficient of resistance is -50 to -10 ppm / ℃ at 20–60℃, and the average temperature coefficient of resistance is -100 to -60 ppm / ℃ at 20–120℃.

2. A method for preparing a negative temperature coefficient copper-manganese-silicon alloy as described in claim 1, characterized in that, Includes the following steps: 1) Vacuum melting The components are taken according to the proportions of the alloy described in claim 1, and after vacuum melting and casting, an ingot is obtained; 2) Hot forging and homogenization annealing The ingot is hot forged to obtain a slab; the slab is then subjected to homogenization annealing to obtain a slab after homogenization annealing. 3) Initial roughing and first recrystallization annealing The slab after homogenization annealing is rolled to obtain a sheet; the sheet is then subjected to a first recrystallization annealing treatment to obtain a sheet after the first recrystallization annealing treatment. 4) Cold rolling and second recrystallization annealing The sheet metal after the first recrystallization annealing treatment is cold rolled to obtain a rough-rolled strip billet; the rough-rolled strip billet is then subjected to a second recrystallization annealing treatment to obtain a rough-rolled strip billet after the second recrystallization annealing treatment. 5) Finished product rolling and recrystallization annealing The rough-rolled strip billet after the second recrystallization annealing treatment is cold-rolled to obtain the finished strip billet; the finished strip billet is then subjected to finished recrystallization annealing treatment to obtain the negative temperature coefficient copper-manganese-silicon alloy finished strip.

3. The method for preparing a negative temperature coefficient copper-manganese-silicon alloy according to claim 2, characterized in that, In step 1), the vacuum degree of the melting process is <100Pa.

4. The method for preparing a negative temperature coefficient copper-manganese-silicon alloy according to claim 2, characterized in that, In step 2), the hot forging temperature is 600-850℃, the homogenization annealing temperature is 680-780℃, the holding time is 5-10h, and rapid cooling is performed.

5. The method for preparing a negative temperature coefficient copper-manganese-silicon alloy according to claim 2, characterized in that, In step 3), the first recrystallization annealing treatment is carried out under a nitrogen protective atmosphere, with an annealing temperature of 650-750°C, a holding time of 4.5-6.5 hours, and rapid cooling.

6. The method for preparing a negative temperature coefficient copper-manganese-silicon alloy according to claim 2, characterized in that, In step 4), the second recrystallization annealing treatment is carried out under the protective atmosphere of ammonia decomposition gas, with an annealing temperature of 650-850℃, a holding time of 2-20 minutes, and air cooling.

7. The method for preparing a negative temperature coefficient copper-manganese-silicon alloy according to claim 2, characterized in that, In step 5), the recrystallization annealing treatment of the finished product is carried out in the following manner: under the protective atmosphere of ammonia decomposition gas, the annealing temperature is 650-800℃, the holding time is 1-10min, and then air cooling is performed.

8. The application of a negative temperature coefficient copper-manganese-silicon alloy as described in claim 1 in the manufacture of precision resistive elements under wide temperature range conditions.

Images