A manganese-copper material for precision resistors and a method for producing the same

Abstract

The application discloses a manganese white copper material for precision resistance and a preparation method thereof. The material is composed of 15-20 wt% of Ni element, 18-25 wt% of Mn element, 1.0-2.0 wt% of Sn element, 0.2-1.0 wt% of Ti element, 1.5-2.5 wt% of Ag element and the rest of Cu plus inevitable impurities, wherein the mass ratio of Mn to Ni is greater than 1.2. The application reduces the resistance temperature coefficient of the alloy by adding micro-alloy elements such as Sn, Ti and Ag and introducing low-resistance NiMn phase particles; and the uniformity of the microstructure of the manganese white copper finished product is further improved and the performance stability of the alloy finished product is improved by adopting a vacuum horizontal continuous casting technology and a deformation heat treatment process optimization and the like.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal processing and relates to a manganese cupronickel material for precision resistors and its processing and preparation method. Background Technology

[0002] Manganese cupronickel is a copper-based alloy material with high resistance and a high temperature coefficient of resistance. It is mainly used to make resistive components such as potentiometers, shunts, and precision bridges, and is widely used in precision instruments, electronics, electrical engineering, and information communication.

[0003] With the development of high precision and high stability in precision resistive components, higher requirements are being placed on the temperature coefficient of resistance and performance stability of precision resistive alloy materials. How to reduce the temperature coefficient of resistance of manganese cupronickel has become a key research focus for this type of material. Summary of the Invention

[0004] Currently, adding alloying elements is the main method to reduce the temperature coefficient of resistance of manganese copper. The addition of elements such as germanium, aluminum, and silicon can effectively reduce the temperature coefficient of resistance of manganese cupronickel and improve its performance stability.

[0005] Because nickel and manganese in manganese cupronickel oxidize during high-temperature smelting, the nickel and manganese content in the alloy billet is difficult to control, significantly affecting the composition and performance stability of the manganese cupronickel. Furthermore, nickel and manganese oxides easily exist as impurities in the alloy billet, and these coarse oxides severely affect the plasticity and strength of manganese cupronickel products. Therefore, how to avoid the oxidation of nickel and manganese during the casting process to improve the quality of the billet is a key issue that needs to be addressed in manganese cupronickel production.

[0006] As can be seen from the above application data of manganese copper, the comprehensive performance and preparation process of manganese cupronickel need further optimization to meet the increasingly complex service environments. This patent aims to design a new type of manganese cupronickel material through microalloying element control, and further improve the microstructure and performance stability of manganese cupronickel by adopting vacuum horizontal continuous casting technology and optimizing deformation heat treatment process, so as to prepare high-strength, low-temperature-coefficient manganese cupronickel for precision resistors.

[0007] The purpose of this invention is to provide a precision resistor material with a novel and unique structure, convenient use, and the ability to organically fit the packaged goods; the specific technical solution is as follows:

[0008] A low temperature coefficient of resistance and high strength manganese cupronickel material, wherein the composition of the manganese cupronickel is: 15-20 wt% Ni, 18-25 wt% Mn, 1.5-2.5 wt% Ag, 1.0-2.0 wt% Sn, 0.2-1.0 wt% Ti, and the remainder Cu plus unavoidable impurities, wherein the mass ratio of Mn to Ni is greater than 1.2.

[0009] The preparation method of the above-mentioned manganese cupronickel material includes the following steps:

[0010] Step 1: Add the raw materials to the melting furnace of the vacuum continuous melting and casting system, and evacuate the melting furnace and holding furnace in the vacuum continuous melting and casting system to keep the vacuum degree of the melting furnace and holding furnace below 0.1 Pa; then, introduce argon or nitrogen into the melting furnace and holding furnace to make the pressure inside the furnace 0.07-0.1 MPa.

[0011] Step 2: Raise the temperature in the melting furnace described in Step 1 to 1150-1300℃. After the raw materials are completely melted, pour them into a holding furnace for holding at 1100-1250℃. After the molten metal is held in the holding furnace for 3-10 minutes, it is pulled out as a manganese cupronickel alloy billet through a horizontal continuous casting device.

[0012] Step 3: Roll the manganese cupronickel ingot described in Step 2 into a die, with a rolling strain of 1.2 to 4.0.

[0013] Step 4: Anneal the manganese cupronickel described in Step 3. Annealing is carried out under a protective atmosphere such as argon or nitrogen, at a temperature of 500-800℃, and for a time of 10-60 minutes.

[0014] Step 5: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese cupronickel in the heat-treated state described in Step 4, the oxides on the alloy surface are removed.

[0015] Step 6: Draw the manganese cupronickel alloy described in Step 5 with a drawing strain of 2.0 to 5.0.

[0016] Step 7: Anneal the manganese cupronickel alloy described in Step 6. Annealing is carried out under a protective atmosphere such as argon or nitrogen. The annealing temperature is 500-800℃, the annealing time is 10-60 min, and the cooling rate during the cooling process after holding the temperature is 5-40℃ / min.

[0017] Step 8: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese white copper in the heat-treated state described in Step 7, the oxides on the alloy surface are removed.

[0018] Step 9: Perform multiple drawing passes on the manganese cupronickel described in Step 8 until it reaches the finished product size.

[0019] Step 10: Perform aging treatment on the manganese cupronickel described in Step 9. The aging is carried out under an argon or nitrogen protective atmosphere, at an aging temperature of 300℃~450℃, and for a holding time of 0.5~8h.

[0020] Step 11: The manganese cupronickel in the annealed state described in Step 10 is subjected to acid washing, alkali washing, saponification treatment and drying in sequence to obtain the finished manganese cupronickel product.

[0021] Furthermore, in step one, pure copper, pure manganese, pure nickel, pure titanium, pure silver, and pure tin with a purity of not less than 99.95% are used as raw materials.

[0022] Furthermore, during the traction process of the manganese cupronickel alloy rod blank in step two, the horizontal traction speed is 3-10 mm / s, the pause time is 0.1-0.4 s, and the cooling water flow rate is 100-300 L / min; the diameter of the obtained manganese cupronickel alloy rod blank is 8 mm-20 mm, and the oxygen content of the rod blank is less than 8 ppm.

[0023] Furthermore, the manganese cupronickel described in step seven is mainly composed of a copper-based solid solution, with a volume fraction of the copper-based solid solution phase greater than 99%; at this point, the alloy elongation is greater than 35%.

[0024] Furthermore, the volume fraction of the discontinuous desolvation structure formed in the manganese cupronickel alloy in step ten is less than 20%; the KAM value of the longitudinal section of the manganese cupronickel alloy determined by the EBSD method is between 0.8 and 2.8; a large number of NiMn phase particles are dispersed and precipitated in the alloy matrix, the average particle size of the NiMn phase particles is 3 to 32 nm, and the volume fraction of the NiMn phase is about 3% to 20%.

[0025] In this invention, the strain η is calculated according to the formula η=ln(A0 / A), where A0 is the cross-sectional area of ​​the alloy before deformation and A is the cross-sectional area of ​​the alloy after deformation.

[0026] The manganese copper alloy of this invention has a KAM (Kernel Average Misorientation) value that reflects the average orientation difference of local micro-regions within the material. By statistically analyzing the Kernel Average Misorientation of these micro-regions, the dislocation density within the alloy can be effectively reflected; a higher KAM value indicates a higher dislocation density. In this invention, the KAM value is obtained using EBSD measurements. Furthermore, the average grain size of the alloy is derived from the statistical results of EBSD.

[0027] The present invention has the following beneficial effects:

[0028] (1) By adding alloying elements such as Ti, Ag and Sn, the above three microalloying elements can be dissolved in the copper matrix in the form of solid solution atoms to form a substitution solid solution. In particular, when the mass ratio of Mn to Ni is greater than 1.2, the manganese cupronickel alloy has higher resistivity and lower temperature coefficient of resistance. In addition, the addition of alloying elements such as Ti, Ag and Sn can effectively suppress the formation of discontinuous desolvation structure, thereby improving the microstructure uniformity of manganese cupronickel products, improving the performance stability of manganese cupronickel, and reducing the temperature coefficient of resistance of manganese cupronickel.

[0029] (2) The present invention uses vacuum continuous melting and casting technology to prepare manganese cupronickel billets. Since the melting and casting are carried out under atmosphere protection conditions, the oxygen content in the alloy can be effectively reduced. In addition, the vacuum continuous melting and casting technology can prepare manganese cupronickel alloy billets of various sizes and specifications.

[0030] (3) The method for preparing manganese cupronickel of the present invention includes roll forming, drawing, recrystallization annealing, and aging. By controlling the strain during drawing, the dislocation density within the grains can be effectively controlled, thereby improving the resistivity of the alloy. During the annealing process, manganese cupronickel undergoes a recovery recrystallization reaction, thereby forming a recrystallized structure, which can control the grain size of the alloy to a certain extent and weaken the anisotropy of the alloy properties. During the aging process, manganese cupronickel can introduce a NiMn phase with low temperature resistivity and high hardness, further improving the temperature coefficient of resistance and strength of the alloy.

[0031] (4) The manganese cupronickel of the present invention has advantages such as low temperature coefficient of resistance, high strength, and high elastic modulus. The manganese cupronickel has a tensile strength of 600-1100 MPa, an elastic modulus of 128-138 GPa, an elongation of 1.5-12%, and a temperature coefficient of resistance α of -3.0 × 10⁻⁶. -5 ℃ -1 ~2.1×10 -5 ℃ -1 The temperature coefficient of resistance β is -8 × 10⁻⁸ -7 ℃ -1 ~-1×10 -7 ℃ -1 The average temperature coefficient of resistance in the range of 20℃ to 120℃ -60×10 -6 ℃ -1 ~-5.0×10 -6 ℃ -1 It has excellent overall performance. Attached Figure Description

[0032] Figure 1 The nanoscale NiMn phase particles precipitated during the aging process of the manganese white copper material for precision resistors of this invention;

[0033] Figure 2 The discontinuous desolvation structure formed at the grain boundaries of the manganese white copper material used in precision resistors of this invention. Detailed Implementation

[0034] To further illustrate the present invention, preferred embodiments are described below with reference to examples. The descriptions of the embodiments are merely for further illustrating the features and advantages of the present invention and should not be construed as limiting the present invention in any way.

[0035] Example 1

[0036] A high-strength, low-resistivity temperature coefficient manganese cupronickel comprises Cu, Ni, Mn, Sn, Ag, Ti, and unavoidable impurities. The mass proportions of each component are as follows: Ni 15 wt%, Mn 20 wt%, Sn 1.5 wt%, Ti 0.4 wt%, Ag 1.5 wt%, with the balance being copper and unavoidable impurities, wherein the total impurity content is less than 50 ppm. The mass ratio of Mn to Ni is 1.33. The specific process steps for preparing the above-mentioned manganese cupronickel include:

[0037] Step 1: Using pure copper, pure manganese, pure nickel, pure titanium, pure silver, and pure tin with a purity of not less than 99.95% as raw materials, add the raw materials to the melting furnace of the vacuum continuous melting and casting system. Evacuate the melting furnace and holding furnace in the vacuum continuous melting and casting system to maintain the vacuum degree of the melting furnace and holding furnace below 0.1 Pa. Subsequently, argon gas is introduced into the melting furnace and holding furnace to make the pressure inside the furnace 0.095 MPa.

[0038] Step 2: Raise the temperature in the melting furnace described in Step 1 to 1200℃. After the raw materials are completely melted, pour them into a holding furnace for heat preservation at 1150℃. After the molten metal is held in the holding furnace for 5 minutes, a manganese cupronickel alloy billet with a diameter of Φ12mm is drawn out using a horizontal continuous casting device. During the drawing process of the manganese cupronickel alloy billet, the horizontal drawing speed is 4mm / s, the pause time is 0.2s, and the cooling water flow rate is 120L / min. The impurities in the drawn alloy billet include oxygen and sulfur, with an oxygen content of 4.2ppm and a sulfur content of 16ppm.

[0039] Step 3: Roll the manganese white copper ingot described in Step 2 into a wire with a diameter of Φ6mm and a rolling strain of 1.38.

[0040] Step 4: Anneal the manganese cupronickel described in Step 3. The annealing is carried out under an argon atmosphere at a temperature of 700°C for 60 minutes.

[0041] Step 5: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese cupronickel in the heat-treated state described in Step 4, the oxides on the alloy surface are removed.

[0042] Step 6: Draw the manganese white copper alloy described in Step 5 to a diameter of Φ2mm and a drawing strain of 2.2.

[0043] Step 7: Anneal the manganese cupronickel alloy described in Step 6. Annealing is carried out under a protective atmosphere such as argon or nitrogen at a temperature of 700℃ for 60 minutes. The cooling rate during the cooling process after holding at this temperature is 10℃ / min. The resulting annealed manganese cupronickel mainly consists of a copper-based solid solution, with a volume fraction of copper-based solid solution phase greater than 99%. At this point, the elongation of the alloy is 42%.

[0044] Step 8: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese white copper in the heat-treated state described in Step 7, the oxides on the alloy surface are removed.

[0045] Step 9: Perform multiple drawing operations on the manganese cupronickel described in Step 8 until an alloy product with a diameter of Φ1.5mm is obtained, and the drawing strain is 0.58.

[0046] Step 10: Perform aging treatment on the manganese cupronickel described in Step 9. The aging is carried out under an argon protective atmosphere at an aging temperature of 430℃ for 16 hours. At this time, as... Figure 2 As shown, the volume fraction of the discontinuous desolvation structure formed in the manganese cupronickel alloy is 4.0%, and the KAM value of the longitudinal section of the alloy is 0.86; Figure 1 As shown, a large number of NiMn phase particles are dispersed and precipitated in the alloy matrix. The average particle size of the NiMn phase particles is 24.2 nm, and the volume fraction of the NiMn phase is about 12.4%.

[0047] Step 11: The annealed manganese cupronickel from Step 10 is subjected to acid washing, alkali washing, saponification, and drying to obtain the finished manganese cupronickel. At this point, the manganese cupronickel has a room temperature tensile strength of 926 MPa, an elastic modulus of 134 GPa, an elongation of 2.5%, and a temperature coefficient of resistance α of 1.6 × 10⁻⁶. -5 ℃ -1 The temperature coefficient of resistance β is -3.4 × 10⁻⁶. -7 ℃ -1 The average temperature coefficient of resistance in the range of 20℃ to 120℃ -1.7×10 -5 ℃ -1 .

[0048] Example 2

[0049] A high-strength, low-resistivity temperature coefficient manganese cupronickel comprises Cu, Ni, Mn, Sn, Ag, Ti, and unavoidable impurities. The mass proportions of each component are as follows: Ni 15 wt%, Mn 25 wt%, Sn 1.8 wt%, Ti 0.8 wt%, Ag 2.0 wt%, with the balance being copper and unavoidable impurities, wherein the total impurity content is less than 50 ppm. The mass ratio of Mn to Ni is 1.66. The specific process steps for preparing the above-mentioned manganese cupronickel include:

[0050] Step 1: Using pure copper, pure manganese, pure nickel, pure titanium, pure silver, and pure tin with a purity of not less than 99.95% as raw materials, add the raw materials to the melting furnace of the vacuum continuous melting and casting system. Evacuate the melting furnace and holding furnace in the vacuum continuous melting and casting system to maintain the vacuum degree of the melting furnace and holding furnace below 0.1 Pa. Subsequently, argon gas is introduced into the melting furnace and holding furnace to make the pressure inside the furnace 0.09 MPa.

[0051] Step 2: Raise the temperature in the melting furnace described in Step 1 to 1200℃. After the raw materials are completely melted, pour them into a holding furnace for heat preservation at 1150℃. After the molten metal is held in the holding furnace for 5 minutes, it is drawn out into a manganese cupronickel alloy billet with a diameter of Φ12mm using a horizontal continuous casting device. During the drawing process of the manganese cupronickel alloy billet, the horizontal drawing speed is 4mm / s, the pause time is 0.2s, and the cooling water flow rate is 120L / min. The impurity elements in the drawn alloy billet include oxygen and sulfur, with an oxygen content of 5.6ppm and a sulfur content of 14ppm.

[0052] Step 3: Roll the manganese white copper ingot described in Step 2 into a wire with a diameter of Φ6mm and a rolling strain of 1.38.

[0053] Step 4: Anneal the manganese cupronickel described in Step 3. The annealing is carried out under an argon atmosphere at a temperature of 700°C for 60 minutes.

[0054] Step 5: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese cupronickel in the heat-treated state described in Step 4, the oxides on the alloy surface are removed.

[0055] Step 6: Draw the manganese white copper alloy described in Step 5 to a diameter of Φ2mm and a drawing strain of 2.2.

[0056] Step 7: Anneal the manganese cupronickel alloy described in Step 6. Annealing is carried out under a protective atmosphere such as argon or nitrogen at a temperature of 650℃ for 60 minutes. The cooling rate during the cooling process after holding at this temperature is 8℃ / min. The resulting annealed manganese cupronickel mainly consists of a copper-based solid solution, with a volume fraction of copper-based solid solution phase greater than 99%. At this point, the elongation of the alloy is 44%.

[0057] Step 8: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese white copper in the heat-treated state described in Step 7, the oxides on the alloy surface are removed.

[0058] Step 9: Perform multiple drawing operations on the manganese cupronickel described in Step 8 until an alloy product with a diameter of Φ1mm is obtained, and the drawing strain is 1.39.

[0059] Step 10: The manganese cupronickel described in Step 9 is subjected to aging treatment. The aging is carried out under an argon protective atmosphere at an aging temperature of 450℃ for 10 hours. At this time, the volume fraction of the discontinuous desolvation structure formed in the manganese cupronickel alloy is 1.6%, and the KAM value of the longitudinal section of the alloy is 1.2. A large number of NiMn phase particles are dispersed and precipitated in the alloy matrix. The average particle size of the NiMn phase particles is 19.3 nm, and the volume fraction of the NiMn phase is approximately 10.5%.

[0060] Step 11: The annealed manganese cupronickel from Step 10 is subjected to acid washing, alkali washing, saponification, and drying to obtain the finished manganese cupronickel. At this point, the manganese cupronickel has a room temperature tensile strength of 1142 MPa, an elastic modulus of 134 GPa, an elongation of 4.5%, and a temperature coefficient of resistance α of 1.3 × 10⁻⁶. -5 ℃ -1 The temperature coefficient of resistance β is -2.1 × 10⁻⁶. -7 ℃ -1 The average temperature coefficient of resistance in the range of 20℃ to 120℃ -1.4×10 -5 ℃ -1 .

[0061] Example 3

[0062] A high-strength, low-resistivity temperature coefficient manganese cupronickel comprises Cu, Ni, Mn, Sn, Ag, Ti, and unavoidable impurities. The mass proportions of each component are as follows: Ni 16 wt%, Mn 25 wt%, Sn 2.0 wt%, Ti 1.0 wt%, Ag 2.5 wt%, with the balance being copper and unavoidable impurities, wherein the total impurity content is less than 50 ppm. The mass ratio of Mn to Ni is 1.56. The specific process steps for preparing the above-mentioned manganese cupronickel include:

[0063] Step 1: Using pure copper, pure manganese, pure nickel, pure titanium, pure silver, and pure tin with a purity of not less than 99.95% as raw materials, add the raw materials to the melting furnace of the vacuum continuous melting and casting system. Evacuate the melting furnace and holding furnace in the vacuum continuous melting and casting system to maintain the vacuum degree of the melting furnace and holding furnace below 0.1 Pa. Subsequently, argon gas is introduced into the melting furnace and holding furnace to make the pressure inside the furnace 0.095 MPa.

[0064] Step 2: Raise the temperature in the melting furnace described in Step 1 to 1200℃. After the raw materials are completely melted, pour them into a holding furnace for heat preservation at 1150℃. After the molten metal is held in the holding furnace for 5 minutes, a manganese cupronickel alloy billet with a diameter of Φ16mm is drawn out using a horizontal continuous casting device. During the drawing process of the manganese cupronickel alloy billet, the horizontal drawing speed is 4mm / s, the pause time is 0.2s, and the cooling water flow rate is 260L / min. The impurity elements in the drawn alloy billet include oxygen and sulfur, with an oxygen content of 4.8ppm and a sulfur content of 21ppm.

[0065] Step 3: Roll the manganese white copper ingot described in Step 2 into a wire with a diameter of Φ6mm and a rolling strain of 1.96.

[0066] Step 4: Anneal the manganese cupronickel described in Step 3. The annealing is carried out under an argon atmosphere at a temperature of 650°C for 60 minutes.

[0067] Step 5: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese cupronickel in the heat-treated state described in Step 4, the oxides on the alloy surface are removed.

[0068] Step 6: Draw the manganese white copper alloy described in Step 5 to a diameter of Φ2mm and a drawing strain of 2.2.

[0069] Step 7: Anneal the manganese cupronickel alloy described in Step 6. Annealing is carried out under a protective atmosphere such as argon or nitrogen at a temperature of 650℃ for 60 minutes. The cooling rate during the cooling process after holding at this temperature is 10℃ / min. The resulting annealed manganese cupronickel mainly consists of a copper-based solid solution, with a volume fraction of copper-based solid solution phase greater than 99%. At this point, the elongation of the alloy is 45%.

[0070] Step 8: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese white copper in the heat-treated state described in Step 7, the oxides on the alloy surface are removed.

[0071] Step 9: Perform multiple drawing operations on the manganese cupronickel described in Step 8 until an alloy product with a diameter of Φ0.9mm is obtained, and the drawing strain is 1.6.

[0072] Step 10: The manganese cupronickel described in Step 9 is subjected to aging treatment. The aging is carried out under an argon protective atmosphere at an aging temperature of 450℃ for 12 hours. At this point, the volume fraction of the discontinuous desolvation structure formed in the manganese cupronickel alloy is 0%, and the KAM value of the longitudinal section of the alloy is 1.6. A large number of NiMn phase particles are dispersed and precipitated in the alloy matrix, with an average particle size of 16.8 nm and a volume fraction of approximately 13.9%.

[0073] Step 11: The annealed manganese cupronickel from Step 10 is subjected to acid washing, alkali washing, saponification, and drying to obtain the finished manganese cupronickel. At this point, the manganese cupronickel has a room temperature tensile strength of 1134 MPa, an elastic modulus of 134 GPa, an elongation of 8.6%, and a temperature coefficient of electrical resistance α of 1.1 × 10⁻⁶. -5 ℃ -1 The temperature coefficient of resistance β is -2.6 × 10⁻⁶. -7 ℃ -1 The average temperature coefficient of resistance in the range of 20℃ to 120℃ -1.5×10 -5 ℃ -1 .

[0074] Example 4

[0075] A high-strength, low-resistivity temperature coefficient manganese cupronickel comprises Cu, Ni, Mn, Sn, Ag, Ti, and unavoidable impurities. The mass proportions of each component are as follows: Ni 20 wt%, Mn 24 wt%, Sn 1.5 wt%, Ti 0.2 wt%, Ag 1.5 wt%, with the balance being copper and unavoidable impurities, wherein the total impurity content is less than 50 ppm. The mass ratio of Mn to Ni is 1.22. The specific process steps for preparing the above-mentioned manganese cupronickel include:

[0076] Step 1: Using pure copper, pure manganese, pure nickel, pure titanium, pure silver, and pure tin with a purity of not less than 99.95% as raw materials, add the raw materials to the melting furnace of the vacuum continuous melting and casting system. Evacuate the melting furnace and holding furnace in the vacuum continuous melting and casting system to maintain the vacuum degree of the melting furnace and holding furnace below 0.1 Pa. Subsequently, argon gas is introduced into the melting furnace and holding furnace to make the pressure inside the furnace 0.09 MPa.

[0077] Step 2: Raise the temperature in the melting furnace described in Step 1 to 1200℃. After the raw materials are completely melted, pour them into a holding furnace for heat preservation at 1150℃. After the molten metal is held in the holding furnace for 10 minutes, a manganese cupronickel alloy billet with a diameter of Φ20mm is drawn out using a horizontal continuous casting device. During the drawing process of the manganese cupronickel alloy billet, the horizontal drawing speed is 4mm / s, the pause time is 0.2s, and the cooling water flow rate is 240L / min. The impurity elements in the drawn alloy billet include oxygen and sulfur, with an oxygen content of 5.8ppm and a sulfur content of 24ppm.

[0078] Step 3: Roll the manganese white copper ingot described in Step 2 into a wire with a diameter of Φ8mm and a rolling strain of 1.83.

[0079] Step 4: Anneal the manganese cupronickel described in Step 3. The annealing is carried out under an argon atmosphere at a temperature of 600°C for 60 minutes.

[0080] Step 5: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese cupronickel in the heat-treated state described in Step 4, the oxides on the alloy surface are removed.

[0081] Step 6: Draw the manganese white copper alloy described in Step 5 to a diameter of Φ3mm and a drawing strain of 1.96.

[0082] Step 7: Anneal the manganese cupronickel alloy described in Step 6. Annealing is carried out under a protective atmosphere such as argon or nitrogen at a temperature of 650℃ for 60 minutes. The cooling rate during the cooling process after holding at this temperature is 6℃ / min. The resulting annealed manganese cupronickel mainly consists of a copper-based solid solution, with a volume fraction of copper-based solid solution phase greater than 99%. At this point, the elongation of the alloy is 42%.

[0083] Step 8: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese white copper in the heat-treated state described in Step 7, the oxides on the alloy surface are removed.

[0084] Step 9: Perform multiple drawing operations on the manganese cupronickel described in Step 8 until an alloy product with a diameter of Φ1mm is obtained, and the drawing strain is 2.1.

[0085] Step 10: The manganese cupronickel described in Step 9 is subjected to aging treatment. The aging is carried out under an argon protective atmosphere at an aging temperature of 400℃ for 4 hours. At this time, the volume fraction of the discontinuous desolvation structure formed in the manganese cupronickel alloy is 5.8%, and the KAM value of the longitudinal section of the alloy is 2.4. A large number of NiMn phase particles are dispersed and precipitated in the alloy matrix. The average particle size of the NiMn phase particles is 6.4 nm, and the volume fraction of the NiMn phase is approximately 8.5%.

[0086] Step 11: The annealed manganese cupronickel from Step 10 is subjected to acid washing, alkali washing, saponification, and drying to obtain the finished manganese cupronickel. At this point, the manganese cupronickel has a room temperature tensile strength of 856 MPa, an elastic modulus of 131 GPa, an elongation of 2.5%, and a temperature coefficient of electrical resistance α of -1.7 × 10⁻⁶. -5 ℃ -1 The temperature coefficient of resistance β is -3.8 × 10⁻⁶. -7 ℃ -1 The average temperature coefficient of resistance in the range of 20℃ to 120℃ -2.1×10 -5 ℃ -1 .

[0087] Comparative Example

[0088] A type of manganese cupronickel comprises elements such as Cu, Ni, and Mn, as well as unavoidable impurities. The mass proportions of each component are as follows: Ni 20 wt%, Mn 20 wt%, with the balance being copper and unavoidable impurities, wherein the total impurity content is less than 50 ppm. The mass ratio of Mn to Ni is 1. The specific process steps for preparing the above-mentioned manganese cupronickel include:

[0089] Step 1: Using pure copper, pure manganese, and pure nickel with a purity of not less than 99.95% as raw materials, add the raw materials to the smelting furnace of the vacuum continuous smelting and casting system. Evacuate the smelting furnace and holding furnace in the vacuum continuous smelting and casting system to maintain the vacuum degree of the smelting furnace and holding furnace below 0.1 Pa. Subsequently, argon gas is introduced into the smelting furnace and holding furnace to make the pressure inside the furnace 0.095 MPa.

[0090] Step 2: Raise the temperature in the melting furnace described in Step 1 to 1200℃. After the raw materials are completely melted, pour them into a holding furnace for heat preservation at 1150℃. After the molten metal is held in the holding furnace for 5 minutes, a manganese cupronickel alloy billet with a diameter of Φ12mm is drawn out using a horizontal continuous casting device. During the drawing process of the manganese cupronickel alloy billet, the horizontal drawing speed is 4mm / s, the pause time is 0.2s, and the cooling water flow rate is 120L / min. The impurity elements in the drawn alloy billet include oxygen and sulfur, with an oxygen content of 7.4ppm and a sulfur content of 20ppm.

[0091] Step 3: Roll the manganese white copper ingot described in Step 2 into a wire with a diameter of Φ6mm and a rolling strain of 1.38.

[0092] Step 4: Anneal the manganese cupronickel described in Step 3. The annealing is carried out under an argon atmosphere at a temperature of 700°C for 60 minutes.

[0093] Step 5: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese cupronickel in the heat-treated state described in Step 4, the oxides on the alloy surface are removed.

[0094] Step 6: Draw the manganese white copper alloy described in Step 5 to a diameter of Φ2mm and a drawing strain of 2.2.

[0095] Step 7: Anneal the manganese cupronickel alloy described in Step 6. Annealing is carried out under a protective atmosphere such as argon or nitrogen at a temperature of 700℃ for 60 minutes. The cooling rate during the cooling process after holding at this temperature is 10℃ / min. The resulting annealed manganese cupronickel mainly consists of a copper-based solid solution, with a volume fraction of copper-based solid solution phase greater than 99%. At this point, the elongation of the alloy is 35%.

[0096] Step 8: After sequentially performing acid washing, alkali washing, saponification treatment and drying on the manganese white copper in the heat-treated state described in Step 7, the oxides on the alloy surface are removed.

[0097] Step 9: Perform multiple drawing operations on the manganese cupronickel described in Step 8 until an alloy product with a diameter of Φ1.5mm is obtained, and the drawing strain is 0.58.

[0098] Step 10: The manganese cupronickel described in Step 9 is subjected to aging treatment. The aging is carried out under an argon protective atmosphere at an aging temperature of 430℃ for 16 hours. At this point, the volume fraction of the discontinuous desolvation structure formed in the manganese cupronickel alloy is 24%, and the KAM value of the longitudinal section of the alloy is 0.8. A large number of NiMn phase particles are dispersed and precipitated in the alloy matrix, with an average particle size of 34.2 nm and a volume fraction of approximately 16.1% for the NiMn phase.

[0099] Step 11: The annealed manganese cupronickel from Step 10 is subjected to acid washing, alkali washing, saponification, and drying to obtain the finished manganese cupronickel. At this point, the manganese cupronickel has a room temperature tensile strength of 839 MPa, an elastic modulus of 134 GPa, an elongation of 1.0%, and a temperature coefficient of resistance α of 2.0 × 10⁻⁶. -5 ℃ -1 The temperature coefficient of resistance β is -4.4 × 10⁻⁶. -7 ℃ -1 The average temperature coefficient of resistance in the range of 20℃ to 120℃ -2.4×10 -5 ℃ -1 .

[0100] Table 1. Microstructure and performance indicators of the composite materials of the present invention

[0101]

[0102]

[0103] The above examples are only for illustrating the present invention. In addition, there are many other different implementations, which can be conceived by those skilled in the art after understanding the concept of the present invention. Therefore, they will not be listed one by one here.

Claims

1. A method for preparing manganese cupronickel material for precision resistors, characterized in that, The composition of the manganese cupronickel material is as follows: Ni 15~20 wt%, Mn 18~25 wt%, Ag 1.5~2.5 wt%, Sn 1.0~2.0 wt%, Ti 0.2~1.0 wt%, and the remainder Cu plus unavoidable impurities, wherein the mass ratio of Mn to Ni is greater than 1.2; including the following steps: Step 1: Add the raw materials to the melting furnace of the vacuum continuous melting and casting system, and evacuate the melting furnace and holding furnace in the vacuum continuous melting and casting system to keep the vacuum degree of the melting furnace and holding furnace below 0.1 Pa; then, introduce argon or nitrogen into the melting furnace and holding furnace to make the pressure inside the furnace 0.07~0.1 MPa. Step 2: Raise the temperature in the melting furnace described in Step 1 to 1150~1300℃. After the raw materials are completely melted, pour them into the holding furnace for holding at 1100~1250℃. After the molten metal is held in the holding furnace for 3~10 minutes, it is pulled out as a manganese cupronickel alloy billet through a horizontal continuous casting device. Step 3: Roll the manganese cupronickel alloy rod blank described in Step 2 into a roll pass with a rolling strain of 1.2~4.

0. Step 4: Anneal the manganese cupronickel described in Step 3. The annealing is carried out under an argon or nitrogen protective atmosphere at a temperature of 500-800°C for 10-60 minutes. Step 5: After annealing in Step 4, the manganese cupronickel is subjected to pickling, alkali washing, saponification and drying in sequence to remove oxides from the alloy surface; Step 6: Draw the manganese cupronickel alloy described in Step 5, with a drawing strain of 2.0~5.

0. Step 7: Anneal the manganese cupronickel alloy described in Step 6. The annealing is carried out under an argon or nitrogen protective atmosphere. The annealing temperature is 500~800℃, the annealing time is 10~60min, and the cooling rate during the cooling process after holding the temperature is 5~40℃ / min. Step 8: After annealing in Step 7, the manganese cupronickel is subjected to pickling, alkali washing, saponification and drying in sequence to remove oxides from the alloy surface. Step 9: Perform multiple drawing passes on the manganese cupronickel described in Step 8 until it reaches the finished product size; Step 10: Aging treatment is performed on the manganese cupronickel described in Step 9. The aging is carried out under an argon or nitrogen protective atmosphere, at an aging temperature of 300℃~450℃, and for a holding time of 0.5~8 h. Step 11: After the manganese white copper in Step 10 has undergone aging treatment, it is subjected to acid washing, alkali washing, saponification treatment and drying in sequence to obtain the finished manganese white copper product.

2. The method for preparing manganese cupronickel material for precision resistors as described in claim 1, characterized in that, In step one, pure copper, pure manganese, pure nickel, pure titanium, pure silver, and pure tin with a purity of not less than 99.95% are used as raw materials.

3. The method for preparing manganese cupronickel material for precision resistors as described in claim 1, characterized in that, During the traction process of the manganese cupronickel alloy rod blank in step two, the horizontal traction speed is 3~10mm / s, the pause time is 0.1~0.4s, and the cooling water flow rate is 100~300 L / min.

4. The method for preparing manganese cupronickel material for precision resistors as described in claim 1, characterized in that, The manganese cupronickel obtained in step seven is mainly composed of copper-based solid solution, with a volume fraction of copper-based solid solution phase greater than 99% and an alloy elongation greater than 35%.

5. The method for preparing manganese cupronickel material for precision resistors as described in claim 1, characterized in that, The volume fraction of the discontinuous desolvation structure formed in the manganese cupronickel alloy obtained in step ten is less than 20%; the KAM value of the longitudinal section of the manganese cupronickel alloy determined by the EBSD method is between 0.8 and 2.8; a large number of NiMn phase particles are dispersed in the alloy matrix, the average particle size of the NiMn phase particles is 3~32 nm, and the volume fraction of the NiMn phase is 3%~20%.

6. A manganese cupronickel material for precision resistors, characterized in that, Prepared by the preparation method according to any one of claims 1 to 5.

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