High-strength and high-plasticity Cu-based conductive alloy and preparation method thereof

Abstract

The application discloses a high-strength and high-plasticity Cu-based conductive alloy and a preparation method thereof, and belongs to the field of high-performance copper alloys. The atomic percentage of the copper alloy composition is as follows: Ni: 14.5-15.5 at.%, Al: 4.0-5.0 at.%, Sn: 0.15-0.7 at.%, Si: 0-0.5 at.%, Fe: 0-0.4 at.%, Co: 0-0.4 at.%, and the rest is Cu. Through accurate component design and reasonable processing process matching, multi-level grain size distribution and multiple high-density nanoscale coherent precipitated phase strengthening are introduced to improve the strength and plasticity of the alloy. The electrical conductivity of the series of alloys is 9.5-12.0% IACS, the hardness is 280-330 HV, the ultimate tensile strength is 1000-1150 MPa, the yield strength is 920-1120 MPa, and the elongation is 10.0-18.0%.

Description

TECHNICAL FIELD

[0001] The application relates to a high-strength and high-plasticity Cu-based conductive alloy and a preparation method thereof, and belongs to the technical field of high-performance copper alloys. BACKGROUND

[0002] High-strength conductive copper alloys are widely used in the automobile, electric appliance and electronic industries, and are important materials for manufacturing high-end instruments and electronic components. The most typical one is the age-hardened Cu-Be alloy, which has high strength, good electrical conductivity, good wear resistance and fatigue resistance. For example, the C17200 alloy has a strength of 1330 MPa and an electrical conductivity of 22% IACS, and can meet most use requirements at room temperature. However, the alloy produces toxic dust during production, and therefore it is increasingly urgent to develop other systems of conductive and elastic Cu alloy materials.

[0003] The Cu-Ni-Al alloy is strengthened by the precipitation of the nanoscale L12 ordered structure Ni3Al phase (a=0.3572 nm), and the strength of the alloy can reach 1000 MPa after deformation processing, and the wear resistance and corrosion resistance are good, and the Cu-Ni-Al alloy is expected to replace the Cu-Be alloy. Further trace addition of Si elements in the Cu-Ni-Al alloy, the ultimate tensile strength of the alloy is 1180 MPa, the yield strength is 1133 MPa, and the alloy has a certain electrical conductivity, but the elongation is only 3.6%, which limits the further development and application of the alloy (Shen L, Li Z, Zhang Z, et al. Materials & Design (1980-2015), 2014, 62: 265-270.).

[0004] The strength and plasticity of an alloy are a pair of mechanical properties that are mutually traded off, and the improvement of one will reduce the other. Figure 11 The ashby type strength-plasticity curve diagram of the Cu alloy is shown, and it can be found that the mutual restriction between the strength and the plasticity is also a challenging problem in the Cu alloy. Therefore, developing a plasticity improvement strategy without affecting the yield strength of the Cu-Ni-Al alloy is an important direction for expanding the engineering application of the alloy. SUMMARY

[0005] To solve the problems in the prior art, the application provides a high-strength and high-plasticity Cu-based conductive alloy and a preparation method thereof. Through accurate component design and reasonable processing process matching, multi-level grain size distribution and multiple high-density nanoscale coherent precipitate strengthening are introduced to improve the strength and plasticity of the alloy. To improve the plasticity of the Cu-Ni-Al alloy while ensuring the strength and electrical conductivity of the Cu-Ni-Al alloy, Sn, Si, Co and Fe are selected for collaborative addition. Meanwhile, the multi-level grain size distribution and multiple high-density nanoscale coherent precipitate strengthening of the alloy are realized through a suitable heat treatment process. The heterogeneous organization state of the multi-level grain size distribution ensures the generation of a region combining soft and hard domains in the alloy, and the back stress strengthening generated by the strain coordination between the soft and hard domains is utilized to improve the strength and plasticity of the alloy. The high-density nanoscale coherent precipitate strengthening further improves the strength of the alloy while reducing the solubility of solutes in the matrix, thereby ensuring the electrical conductivity of the alloy.

[0006] The technical scheme adopted by the application is as follows:

[0007] By reasonably selecting the type of coherent precipitate phase, a series of high-strength and high-plasticity Cu-based conductive alloy components are designed. The atomic percentage of the copper alloy component is as follows: Ni: 14.5-15.5 at.%, Al: 4.0-5.0 at.%, Sn: 0.15-0.7 at.%, Si: 0.15-0.5 at.%, Fe: 0.2-0.4 at.%, Co: 0.2-0.4 at.%, and the rest is Cu. The series of alloys improve the strength and plasticity of the alloy through multi-level grain size and multiple high-density nanoscale coherent precipitate phase. The multi-level grain size includes the grain size of the deformation band region, which is 0.5-1 μm, and the grain size of the remaining non-deformation band region, which is 1-20 μm. The types of coherent precipitate phases include Ni3Al, Ni3Sn and Ni2Si. The electrical conductivity of the series of alloys is 9.5-12.0% IACS, the hardness is 280-330 HV, the ultimate tensile strength is 1000-1150 MPa, the yield strength is 920-1120 MPa, and the elongation is 10.0-18.0%.

[0008] The preparation method of the high-strength and high-plasticity Cu-based conductive alloy is as follows:

[0009] (1) Non-consumable vacuum arc melting is adopted, high-purity argon gas is introduced for protection, and the prepared Cu, Ni and Al raw materials with a purity of more than 4N are repeatedly melted to obtain an alloy ingot with uniform composition;

[0010] (2) The as-cast alloy is subjected to solid solution treatment, the holding temperature and time are 1000℃ and 4 hours respectively, and the cooling mode is water quenching; then the solid solution state alloy is cold rolled, and the thickness and deformation amount are controlled, and the thickness deformation amount is 70-90%;

[0011] (3) The cold-rolled alloy is annealed for a short time, the holding temperature and time are 1000 DEG C and 5 minutes respectively, and then water quenched; and then aged, the holding temperature and time are 450 DEG C and 4 hours respectively, and then furnace cooled.

[0012] The beneficial effects of the present application are:

[0013] 1. By reasonably configuring the enthalpy interaction between elements, adding trace elements such as Sn, Si and Fe in Cu-Ni-Al alloy, introducing multiple coherent precipitates such as Ni3Al, Ni2Si, Ni3Sn, etc., the precipitate strengthening effect of the alloy is improved.

[0014] 2. Reasonably configuring the heat treatment process, realizing the multi-level grain size distribution and the precipitation of multiple high-density nanoscale coherent precipitates, the strength and plasticity of the Cu-Ni-Al alloy are synergistically improved.

[0015] The strength and plasticity of the alloy are a pair of mutually balanced mechanical properties, and the improvement of one will reduce the other, and the mutual restriction between strength and plasticity. In the present application, the strength and plasticity of the alloy are synergistically improved by multi-level grain size and multiple high-density nanoscale coherent precipitates; the heterogeneous organization state of multi-level grain size distribution ensures the generation of soft and hard domain combined regions in the alloy, and the back stress strengthening generated by the strain coordination between soft and hard domains is used to simultaneously improve the strength and plasticity of the alloy. The high-density nanoscale coherent precipitate strengthening further improves the strength of the alloy while reducing the solubility of solute in the matrix, ensuring the electrical conductivity of the alloy. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the metallographic structure image of Cu 80.00 Ni 15.00 Al 4.38 Sn 0.62 (at.%) alloy.

[0017] Figure 2 is the engineering stress-engineering strain curve of Cu 80.00 Ni 15.00 Al 4.38 Sn 0.62 (at.%) alloy after aging treatment.

[0018] Figure 3 is the metallographic structure image of Cu 80.00 Ni 15.00 Al 4.38 Si 0.47 Sn 0.15 (at.%) alloy after aging treatment.

[0019] Figure 4 is the engineering stress-engineering strain curve of Cu 80.00Ni 15.00 Al 4.38 Si 0.47 Sn 0.15 (at.%) alloy engineering stress-engineering strain curve.

[0020] Figure 5 Cu after aging treatment 80.00 Ni 15.00 Al 4.38 Si 0.15 Sn 0.47 (at.%) metallographic image of the alloy.

[0021] Figure 6 Cu after aging treatment 80.00 Ni 15.00 Al 4.38 Si 0.15 Sn 0.47 (at.%) alloy engineering stress-engineering strain curve.

[0022] Figure 7 Cu after aging treatment 80.00 Ni 14.69 Al 4.38 Si 0.31 Sn 0.31 Co 0.31 (at.%) metallographic image of the alloy.

[0023] Figure 8 Cu after aging treatment 80.00 Ni 14.69 Al 4.38 Si 0.31 Sn 0.31 Co 0.31 (at.%) alloy engineering stress-engineering strain curve.

[0024] Figure 9 Cu after aging treatment 80.00 Ni 14.69 Al 4.38 Si 0.47 Sn 0.15 Fe 0.31 (at.%) metallographic image of the alloy.

[0025] Figure 10 Cu after aging treatment 80.00 Ni 14.69 Al 4.38 Si 0.47 Sn 0.15 Fe 0.31 (at.%) alloy engineering stress-engineering strain curve.

[0026] Figure 11 Cu alloy in the prior art. DETAILED DESCRIPTION

[0027] The specific embodiments of the present application are described in detail below with reference to the technical solutions.

[0028] Example 1: Cu 80.00 Ni 15.00 Al 4.38 Sn 0.62 (at.%) alloy

[0029] Step one: alloy preparation and microstructure characterization

[0030] The composition of Cu 80.00 Ni 15.00 Al 4.38 Sn 0.62 (at.%) alloy is converted into weight percentage, and the alloy is prepared using 4N pure Cu, Ni and Sn, and 5N pure Al raw materials; a non-consumable vacuum arc melting furnace is used, high-purity Ar gas is introduced for protection, and the prepared alloy raw materials are repeatedly melted for 5 times, and finally the alloy ingot with uniform composition is obtained. The as-cast alloy is subjected to solid solution treatment, the holding temperature and time are 1000℃ and 4 hours respectively, and the cooling method is water quenching. Then the solid solution alloy is cold rolled, and the thickness and deformation amount are controlled, the thickness deformation amount is 70-90%. Finally, the cold rolled alloy is subjected to short-time annealing treatment, the holding temperature and time are 1000℃ and 5 minutes respectively, and the water quenching; then it is subjected to aging treatment, the holding temperature and time are 450℃ and 4 hours respectively, and the furnace cooling.

[0031] Step two: alloy structure and performance characterization

[0032] The metallographic structure is observed by a metallographic microscope, as shown in Figure 1 , showing a variety of grain size distribution. The tensile properties of the alloy are tested by a universal tensile testing machine, and the engineering stress-strain curve is shown in Figure 2 . The electrical conductivity of the alloy is 10.47%IACS, the hardness is 292.5HV, the ultimate tensile strength is 1021MPa, the yield strength is 924MPa, and the elongation is 11.5%.

[0033] Example 2: Cu 80.00 Ni 15.00 Al 4.38 Si 0.47 Sn 0.15 (at.%) alloy

[0034] Step one: alloy preparation and microstructure characterization

[0035] The composition of Cu80.00 Ni 15.00 Al 4.38 Si 0.47 Sn 0.15 The alloy is converted into weight percentage, and the alloy is prepared using raw materials of Cu, Ni, Sn and Si with a purity of 4N and Al with a purity of 5N; a non-consumable vacuum arc melting furnace is used, and high-purity Ar gas is introduced for protection, and the prepared alloy raw materials are repeatedly melted 5 times to finally obtain an alloy ingot with uniform composition. The cast alloy is subjected to solid solution treatment, with a holding temperature and time of 1000°C and 4 hours respectively, and the cooling method is water quenching. The solid solution alloy is then cold rolled, and the thickness and deformation are controlled, with the thickness deformation of 70-90%. Finally, the cold rolled alloy is subjected to a short annealing treatment, with a holding temperature and time of 1000°C and 5 minutes respectively, and water quenching; followed by aging treatment, with a holding temperature and time of 450°C and 4 hours respectively, and furnace cooling.

[0036] Step 2: Characterization of alloy structure and properties

[0037] The metallographic structure was observed using a metallographic microscope. Figure 3 As shown in Figure 2, it shows a variety of grain size distributions. The tensile properties of the alloy were tested using a universal tensile testing machine, and its engineering stress-strain curve is shown in Figure 2. Figure 4 The alloy has electrical conductivity of 11.16% IACS, hardness of 314.9 HV, ultimate tensile strength of 1120 MPa, yield strength of 1010 MPa, and elongation of 15.86%.

[0038] Example 3: Cu 80.00 Ni 15.00 Al 4.38 Si 0.15 Sn 0.47 (at.%) alloy

[0039] Step 1: Alloy preparation and microstructure characterization

[0040] The composition is Cu 80.00 Ni 15.00 Al 4.38 Si 0.15 Sn 0.47(at.%) into weight percentage, using 4N purity Cu, Ni, Sn and Si, 5N purity Al raw materials to prepare the alloy; using a non-consumable vacuum arc melting furnace, high-purity Ar gas protection, repeatedly melting the prepared alloy raw materials 5 times, and finally obtaining an alloy ingot with uniform composition. The as-cast alloy is subjected to solid solution treatment, and the holding temperature and time are 1000°C and 4 hours respectively, and the cooling method is water quenching. Subsequently, the solid solution state alloy is cold rolled, and the thickness and deformation amount are controlled, and the thickness deformation amount is 70-90%. Finally, the cold rolled alloy is subjected to short-time annealing treatment, and the holding temperature and time are 1000°C and 5 minutes respectively, and water quenching; then aging treatment is carried out, and the holding temperature and time are 450°C and 4 hours respectively, and the furnace cooling is carried out.

[0041] Step two: alloy structure and performance characterization

[0042] The metallographic structure is observed by metallographic microscope, which is shown in Figure 5 , showing a variety of grain size distribution. The tensile properties of the alloy are tested by universal tensile testing machine, and the engineering stress-strain curve is shown in Figure 6 . The electrical conductivity of the alloy is 10.24% IACS, the hardness is 314.0 HV, the ultimate tensile strength is 1102 MPa, the yield strength is 1005 MPa, and the elongation is 16.84%.

[0043] Example 4: Cu 80.00 Ni 14.69 Al 4.38 Si 0.31 Sn 0.31 Co 0.31 (at.%) alloy

[0044] Step one: alloy preparation and microstructure characterization

[0045] The composition of Cu 80.00 Ni 14.69 Al 4.38 Si 0.31 Sn 0.31 Co 0.31(at.%) into weight percentage, using Cu, Ni, Sn, Co and Si with purity of 4N, Al with purity of 5N as raw materials to prepare the alloy; using non-consumable vacuum arc melting furnace, high-purity Ar gas protection, repeatedly melting the prepared alloy raw materials for 5 times, finally obtaining alloy ingot with uniform composition. The as-cast alloy was subjected to solid solution treatment, the holding temperature and time were 1000 °C and 4 hours respectively, and the cooling method was water quenching. Then the solid solution alloy was cold rolled, and the thickness and deformation amount were controlled, the thickness deformation amount was 70-90%. Finally, the cold rolled alloy was subjected to short-time annealing treatment, the holding temperature and time were 1000 °C and 5 minutes respectively, water quenching; then aging treatment was carried out, the holding temperature and time were 450 °C and 4 hours respectively, and the furnace cooling was carried out.

[0046] Step two: alloy structure and performance characterization

[0047] The metallographic structure was observed by metallographic microscope, as shown in Figure 7 , showing a variety of grain size distribution. The tensile properties of the alloy were tested by universal tensile testing machine, and the engineering stress-strain curve was as shown in Figure 8 . The electrical conductivity of the alloy was 10.00% IACS, the hardness was 272.6 HV, the ultimate tensile strength was 1098 MPa, the yield strength was 996 MPa, and the elongation was 10.45%.

[0048] Example 5: Cu 80.00 Ni 14.69 Al 4.38 Si 0.47 Sn 0.15 Fe 0.31 (at.%) alloy

[0049] Step one: alloy preparation and microstructure characterization

[0050] The composition of Cu 80.00 Ni 14.69 Al 4.38 Si 0.47 Sn 0.15 Fe 0.31(at.%) into weight percentage, using Cu, Ni, Sn, Fe and Si raw materials with purity of 4N, Al raw material with purity of 5N to prepare the alloy; using non-consumable vacuum arc furnace, high-purity Ar gas is introduced for protection, the prepared alloy raw material is repeatedly melted for 5 times, finally the alloy ingot with uniform composition is obtained. The as-cast alloy is subjected to solid solution treatment, the holding temperature and time are 1000°C and 4 hours respectively, the cooling mode is water quenching. Then the solid solution alloy is cold rolled, and the thickness and deformation amount are controlled, the thickness deformation amount is 70-90%. Finally, the cold rolled alloy is subjected to short-time annealing treatment, the holding temperature and time are 1000°C and 5 minutes respectively, water quenching; then aging treatment is carried out, the holding temperature and time are 450°C and 4 hours respectively, furnace cooling.

[0051] Step two: alloy structure and performance characterization

[0052] The metallographic structure is observed by metallographic microscope, as shown in Figure 9 , a variety of grain size distribution is presented. The tensile properties of the alloy are tested by universal tensile testing machine, the engineering stress-strain curve is as shown in Figure 10 . The electrical conductivity of the alloy is 11.25% IACS, the hardness is 326.3 HV, the ultimate tensile strength is 1093 MPa, the yield strength is 1000 MPa, and the elongation is 17.57%.

Claims

1. A method for preparing a high-strength and high-plasticity Cu-based conductive alloy, characterized by: The atomic percentage of the alloy components is Ni: 14.5-15.5 at.%, Al: 4.0-5.0 at.%, Sn: 0.15-0.7 at.%, Si: 0-0.5 at.%, Fe: 0-0.4 at.%, Co: 0-0.4 at.%, and the remainder is Cu content; The performance indicators of the alloy are: electrical conductivity 9.5-12.0%IACS, hardness 280-330HV, ultimate tensile strength 1000-1150MPa, yield strength 920-1120MPa, elongation 10.0-18.0%; The alloy improves the strength and plasticity of the alloy through multi-level grain size and multiple high-density nano-scale coherent precipitation phases; The grain size, including that in the deformation zone, is 0.5-1 μm, and the grain size in the rest of the region is 1-20 μm. The types of high-density nanoscale coherent precipitates are Ni3Al and Ni3Sn. If the alloy contains Si, the coherent precipitates also include Ni2Si. The preparation method comprises the following steps: (1) Using non-consumable vacuum arc melting, with high-purity argon gas as protection, the prepared raw materials with a purity of more than 4N are repeatedly melted to obtain alloy ingots with uniform composition; (2) The as-cast alloy is subjected to a solution treatment at a holding temperature of 1000°C and a holding time of 4 hours, and the cooling method is water quenching; the solution alloy is then cold rolled, and the thickness and deformation are controlled, with the thickness deformation being 70-90%; (3) The cold-rolled alloy was subjected to a short-time annealing treatment at a holding temperature of 1000°C for 5 minutes, followed by water quenching. Subsequently, the alloy was subjected to an aging treatment at a holding temperature of 450°C for 4 hours, followed by furnace cooling.

2. A high-strength and high-plasticity Cu-based conductive alloy, characterized by: The conductive alloy is prepared by the preparation method according to claim 1.

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