High-strength high-temperature-resistant copper alloy strip and application thereof in AI computing power center

Abstract

This invention relates to the field of copper alloy strip preparation technology, and discloses a high-strength, high-temperature resistant copper alloy strip and its application in AI computing centers. The copper alloy strip comprises, by mass percentage: Ni 0.6%–3.8%, Co 0.9%–1.6%, Si 0.35%–0.85%, Zn 0.03%–0.45%, Sn 0.02%–0.18%, Re 0.001%–0.02%, with the balance being Cu and unavoidable impurities; preferably, it also includes B. The preparation method includes melting and casting according to the proportions, heating in a walking beam furnace, hot rolling, milling, rough rolling, solution treatment, cold rolling, aging treatment, finished product rolling, and finished product annealing. By combining the Ni, Co, and Si precipitation strengthening system with the microstructure regulation effects of Zn, Sn, Re, and B, coarse second-phase particles in the metallographic structure are discretely distributed, and the continuous network of second-phase aggregation regions at grain boundaries are reduced. This results in a copper alloy strip with high electrical conductivity, high tensile strength, high thermal conductivity, and good high-temperature stress retention capability, which is suitable for AI computing center connection, conductive, and heat dissipation components.

Description

Technical Field

[0001] This invention relates to the field of copper alloy strip preparation technology, and discloses a high-strength, high-temperature resistant copper alloy strip and its application in AI computing centers. Background Technology

[0002] As the power density of AI servers, GPU clusters, and high-speed interconnect devices continues to increase, connectors, conductive terminals, busbar connectors, and heat dissipation conductive components within AI computing centers need to withstand high current, high-frequency signal transmission, and localized heat accumulation environments for extended periods. Copper alloy strips, due to their high electrical and thermal conductivity, strength, and processability, are widely used in high-end electronic connection materials and precision conductive structural components. For these applications, materials not only need to meet the processing requirements of stamping, bending, and assembly, but also need to maintain stable dimensional, microstructure, and mechanical properties under long-term thermal exposure and stress loading conditions.

[0003] In existing technologies, common approaches include Cu-Ni-Si, Cu-Co-Si, and Cu-Ni-Co-Si precipitation-strengthened copper alloys. These alloys form fine second phases through solution treatment, cold working, and aging to balance strength and electrical conductivity. Other technologies involve adding trace elements such as Cr, Mg, Ag, Sn, Zn, Fe, or rare earth elements to regulate precipitation behavior, recrystallization behavior, or heat resistance. While these approaches can improve the strength and conductivity of copper alloy strips to some extent, they still present challenges in simultaneously achieving optimal strength, thermal conductivity, and high-temperature stress retention in high-power-density AI computing centers. In order to improve strength, some alloy systems increase the amount of precipitates, which may lead to an increase in coarse second phases or continuous phases at grain boundaries, thereby affecting electrical conductivity, thermal conductivity and long-term thermal stability. Although some low alloy or low Co systems have good electrical conductivity, their strengthening ability and thermal stress retention are insufficient. Although some microalloying schemes improve individual properties, the element compatibility is not clear enough, making it difficult to stably obtain a microstructure that meets the requirements of high strength, high conductivity and high thermal stability at the same time.

[0004] Therefore, in response to the comprehensive requirements of AI computing center connection, conductive and heat dissipation components for high strength, high conductivity, high thermal conductivity and long-term thermal stability, it is necessary to provide a copper alloy strip with a more coordinated composition system, more stable microstructure control and suitable for industrial preparation and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength, high-temperature resistant copper alloy strip to solve the problems mentioned in the background art, so that the copper alloy strip can be used in AI computing centers where the requirements for connection, conductivity, heat dissipation and long-term service stability are high.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-strength, high-temperature resistant copper alloy strip, comprising, by mass percentage: Ni 0.6%–3.8%, Co 0.9%–1.6%, Si 0.35%–0.85%, Zn 0.03%–0.45%, Sn 0.02%–0.18%, Re 0.001%–0.02%, with the balance being Cu and unavoidable impurities.

[0008] Furthermore, by mass percentage, it includes 1%–3% Ni, 1.1%–1.3% Co, 0.55%–0.65% Si, 0.1%–0.3% Zn, 0.05%–0.1% Sn, 0.005%–0.01% Re, with the balance being Cu and unavoidable impurities.

[0009] Furthermore, the mass ratio of the total content of Ni and Co to the content of Si is 3.9:1 to 4.7:1, and the mass ratio of Co to Ni is 0.37:1 to 1.30:1.

[0010] Furthermore, it also includes 0.0005% to 0.01% B, wherein the mass ratio of B to Si is 0.001:1 to 0.018:1, and the mass ratio of Re to B is 0.8:1 to 20:1.

[0011] Furthermore, in the metallographic structure of the copper alloy strip, coarse second-phase particles are discretized, and no continuous network of second-phase aggregates is formed at the grain boundaries.

[0012] Furthermore, the average grain size of the copper matrix in the copper alloy strip is 4μm to 15μm.

[0013] Furthermore, the copper alloy strip has an electrical conductivity of not less than 50% IACS, a tensile strength of not less than 850MPa, a thermal conductivity of not less than 192W / (m·K), and a stress retention rate of not less than 85% under the conditions of 150℃, 1000h, and a loading stress of 0.2% of the yield strength.

[0014] This invention also proposes a method for preparing high-strength, high-temperature resistant copper alloy strip, comprising the following steps:

[0015] S1. Provide Cu source, Ni source, Co source, Si source, Zn source, Sn source, Re source and B source according to the ratio, melt and cast in a melting furnace to obtain ingot or billet;

[0016] S2. The ingot or billet is heated in a walking beam furnace and then hot rolled to obtain a hot rolled billet. The hot rolled billet is then subjected to milling, rough rolling and solution treatment and then cooled to obtain a solution-treated billet.

[0017] S3. The solution-treated billet is subjected to cold rolling, aging treatment, finished product rolling and finished product annealing to obtain the copper alloy strip.

[0018] Furthermore, in step S1, the B source is a Cu-B master alloy, the melting temperature is 1100℃~1300℃, and the casting temperature is 1100℃~1300℃; in step S2, the walking beam furnace heating temperature is 900℃~1000℃, the heating time is 3h~6h, the hot rolling start temperature is 900℃~1000℃, and the hot rolling end temperature is above 600℃.

[0019] Furthermore, in step S2, the milling amount is 0.3mm to 1mm / surface and 1mm to 3mm / side, the solution treatment temperature is 900℃ to 1000℃, and the solution is cooled by air cooling, water cooling, or mist cooling. In step S3, the aging temperature is 400℃ to 550℃, the total deformation of the finished product during rolling is 10% to 50%, and the annealing temperature of the finished product is 350℃ to 550℃.

[0020] Furthermore, the application of a high-strength, high-temperature resistant copper alloy strip, as described above, in AI computing centers.

[0021] The present invention has the following beneficial effects:

[0022] (1) This invention uses Ni, Co, and Si as the main precipitation strengthening elements, and adds Zn, Sn, and Re as auxiliary regulating elements to enable the copper alloy strip to form a more stable strengthened structure after aging treatment and reduce the local enrichment of coarse second phase near the grain boundaries. Through the above composition combination, the copper alloy strip can improve its strength and high-temperature stress retention while maintaining its electrical and thermal conductivity, thereby meeting the long-term service requirements of AI computing center connection, conductive and heat dissipation components.

[0023] (2) This invention maintains a suitable precipitation ratio among Ni, Co, and Si by limiting the total content of Ni and Co to the mass ratio of Si, as well as the mass ratio of Co to Ni. This proportional control can reduce the risk of excessive residue or local enrichment of a single element, making the precipitation-strengthened structure after aging more stable, thereby avoiding the problems of insufficient strength due to insufficient precipitation or decreased electrical and thermal conductivity due to coarsening of the structure in traditional copper alloys.

[0024] (3) This invention provides preferred ratios of B to Si and Re to B. Maintaining an appropriate ratio of B to Si is beneficial for regulating the state of grain boundaries and precipitated phase interfaces; maintaining an appropriate ratio of Re to B is beneficial for reducing interface migration and the tendency of coarse second phase aggregation. The combined effect of the two restricts the continuous second phase at grain boundaries and coarse second phase particles, thereby improving the stability of the strip structure and its ability to retain high-temperature stress.

[0025] (4) By controlling the distribution of coarse second phase particles in the metallographic structure, the present invention makes the identifiable coarse second phase particles discretely distributed and reduces the continuous network second phase aggregation area at the grain boundary, thereby reducing the adverse effects of local structural inhomogeneity, continuous enrichment of grain boundaries and aggregation of coarse particles on electrical conductivity, thermal conductivity and high temperature stress retention. Attached Figure Description

[0026] Figure 1 This is a flowchart of the preparation method of the present invention;

[0027] Figure 2 These are comparative metallographic images of the copper alloy strips obtained in Example 2 and Comparative Example 1 of the present invention. Figure 2 (a) is a metallographic diagram of the copper alloy strip obtained in Example 2. Figure 2 (b) is a metallographic diagram of the copper alloy strip obtained in Comparative Example 1;

[0028] Figure 3 These are comparative metallographic images of the copper alloy strips obtained in Example 4 and Comparative Example 8 of the present invention. Figure 3 (a) is a metallographic diagram of the copper alloy strip obtained in Example 4. Figure 3 (b) is a metallographic diagram of the copper alloy strip obtained in Comparative Example 8. Detailed Implementation

[0029] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention and do not constitute a limitation on the scope defined by the claims. All equivalent substitutions or modifications made without departing from the spirit of the present invention should be considered to fall within the protection scope of the present invention.

[0030] The high-strength, high-temperature resistant copper alloy strip provided by this invention uses Cu as the matrix and adds Ni, Co, and Si as the main precipitation strengthening elements. Ni, Co, and Si form precipitation strengthening structures during solid solution treatment, aging, and subsequent processing, thereby improving the strength of the copper alloy strip and reducing the adverse effects of solid solution atoms in the matrix on electrical and thermal conductivity. Simultaneously, Zn and Sn are added to adjust the microstructure stability of the copper alloy strip during processing and service, and to improve the overall state of the strip during finished product rolling and subsequent heat treatment. Furthermore, Re (rhenium) is added as a trace control element, working in conjunction with B to control the microstructure and grain boundary state near the second phase, resulting in a discrete distribution of identifiable coarse second-phase particles in the metallographic structure and maintaining the copper matrix grain size within a suitable range.

[0031] In a preferred embodiment, the present invention controls the mass ratio of B to Si and the mass ratio of Re to B within a specific range to adjust the microstructure near grain boundaries and the second phase, reduce the continuous network-like second phase aggregation region at grain boundaries, and make the identifiable coarse second phase particles in the metallographic structure discretely distributed; at the same time, the average grain size of the copper matrix is ​​controlled to be 4μm to 15μm. Therefore, the copper alloy strip of the present invention can achieve high tensile strength and good high-temperature stress retention while maintaining high electrical and thermal conductivity.

[0032] The copper alloy strips in the embodiments and comparative examples of this invention were prepared according to the following method. Unless otherwise specified, all samples used the same preparation process, with adjustments only made to the alloy composition, the mass ratio of B to Si, the mass ratio of Re to B, and some process parameters.

[0033] S1. Batching, Melting, and Casting: Weigh out the Cu, Ni, Co, Si, Zn, Sn, Re, and B sources according to the target composition. The Cu source is electrolytic copper. The Si, Re, and B sources can be Cu-Si, Cu-Re, and Cu-B master alloys, respectively, or metallic raw materials capable of stably introducing the corresponding elements. Add all raw materials to a melting furnace for melting at a temperature controlled between 1100℃ and 1300℃. After the melt composition is homogeneous, cast the ingot or billet at a temperature controlled between 1100℃ and 1300℃. For examples or comparative examples where B is not added, the B source is not provided in step S1.

[0034] S2. Walking beam furnace heating, hot rolling, milling, and solution treatment: The ingot or billet is placed in a walking beam furnace for heating. The heating temperature is controlled at 900℃~1000℃, and the heating time is 3h~6h. After exiting the furnace, it is hot rolled. The starting temperature of hot rolling is controlled at 900℃~1000℃, and the ending temperature is controlled at above 600℃ to obtain a hot-rolled billet. Subsequently, the hot-rolled billet is milled, with a surface milling amount of 0.3mm~1mm / surface and a side milling amount of 1mm~3mm / side, to remove the surface oxide layer, surface segregation layer, and edge defect areas of the hot-rolled billet. After milling, the billet is rough rolled to further reduce the billet thickness and form an intermediate rolling state before solution treatment. After rough rolling, solution treatment is performed, with the solution treatment temperature controlled at 900℃~1000℃. After solution treatment, it is cooled by air cooling, water cooling, or mist cooling to obtain a solution-treated billet.

[0035] S3. Cold rolling, aging treatment, finished product rolling, and finished product annealing: The solution-treated billet is cold-rolled to gradually reduce the strip thickness and introduce the deformation structure required for subsequent aging. After cold rolling, aging treatment is performed at a temperature controlled between 400℃ and 550℃ to allow elements such as Ni, Co, and Si to form precipitation strengthening structures. After aging treatment, finished product rolling is performed with a total deformation controlled between 10% and 50%. Subsequently, finished product annealing is performed at a temperature controlled between 350℃ and 550℃ to release residual stress after finished product rolling and stabilize the copper matrix grains and precipitated phase state, thereby obtaining the high-strength, high-temperature resistant copper alloy strip.

[0036] High-strength, high-temperature resistant copper alloy strips for Examples 1 to 7 were prepared according to the chemical composition shown in Table 1. The content of each element is a mass percentage.

[0037] Table 1 Chemical composition of Examples 1 to 7

[0038] Group Ni / % Co / % Si / % Zn / % Sn / % Re / % B / % (Ni+Co):Si Co:Ni B:Si Re:B Example 1 1.21 0.97 0.51 0.083 0.041 0.0031 — 4.27 0.802 — — Example 2 1.83 1.21 0.649 0.21 0.083 0.0061 — 4.68 0.661 — — Example 3 0.81 0.96 0.41 0.041 0.026 0.0013 0.0007 4.32 1.185 0.0017 1.86 Example 4 1.83 1.21 0.649 0.21 0.083 0.0061 0.0031 4.68 0.661 0.0048 1.97 Example 5 2.61 1.31 0.849 0.41 0.163 0.0151 0.0081 4.62 0.502 0.0095 1.86 Example 6 1.51 1.11 0.609 0.151 0.061 0.0041 0.0011 4.3 0.735 0.0018 3.73 Example 7 2.67 1.29 0.849 0.31 0.103 0.0101 0.0061 4.66 0.483 0.0072 1.66

[0039] Note: "—" indicates that the element was not included or that the proportional relationship is not involved.

[0040] Examples 1 through 7 were prepared according to the preparation method of the present invention, and the specific key process parameters are shown in Table 2:

[0041] Table 2 Key process parameters of Examples 1 to 7

[0042] Group Melting temperature / °C Casting temperature / ℃ Walking beam furnace temperature / ℃ Heating time / h Solution temperature / °C Cooling method Aging temperature / ℃ Total deformation of finished product during rolling / % Finished product annealing temperature / ℃ Example 1 1183 1161 927 4.1 933 air-cooled 493 26.3 459 Example 2 1221 1197 951 5.1 953 Water cooling 501 30.7 467 Example 3 1161 1139 919 4.3 923 air-cooled 493 25.7 457 Example 4 1221 1197 951 5.1 953 Water cooling 501 30.7 467 Example 5 1277 1259 983 5.7 977 Water cooling 511 35.3 477 Example 6 1203 1181 943 4.7 941 foggy cold 497 28.5 461 Example 7 1249 1227 971 5.3 971 Water cooling 507 32.5 471

[0043] Copper alloy strips of Comparative Examples 1 to 13 were prepared according to the chemical composition shown in Table 3. The content of each element is a mass percentage.

[0044] Table 3 Chemical composition of Comparative Examples 1 to 13

[0045] Group Ni / % Co / % Si / % Zn / % Sn / % Re / % B / % (Ni+Co):Si Co:Ni B:Si Re:B illustrate Comparative Example 1 1.83 1.21 0.649 — — — — 4.68 0.661 — — Traditional Ni-Co-Si system Comparative Example 2 2.31 0.31 0.701 0.21 0.083 — — 3.74 0.134 — — Low Co system Comparative Example 3 1.83 1.21 0.649 — — — — 4.68 0.661 — — Also contains 0.083% Ag. Comparative Example 4 1.83 1.21 0.649 — 0.083 0.0061 — 4.68 0.661 — — Zn not added Comparative Example 5 1.83 1.21 0.649 0.21 — 0.0061 — 4.68 0.661 — — Sn not joined Comparative Example 6 1.83 1.21 0.649 0.21 0.083 — — 4.68 0.661 — — Not included in Re Comparative Example 7 1.83 1.21 0.649 0.21 0.083 0.0049 0.0003 4.68 0.661 0.0005 16.33 B is below the lower limit. Comparative Example 8 1.83 1.21 0.649 0.21 0.083 0.0152 0.0151 4.68 0.661 0.0233 1.01 B is higher than the upper limit. Comparative Example 9 2.61 1.31 0.849 0.21 0.083 0.0022 0.0007 4.62 0.502 0.0008 3.14 B: Si is below the lower limit Comparative Example 10 1.83 1.21 0.649 0.21 0.083 0.0021 0.0031 4.68 0.661 0.0048 0.677 Re: B is below the lower limit Comparative Example 11 1.83 1.21 0.649 0.21 0.083 0.0191 0.0009 4.68 0.661 0.0014 21.22 Re:B is higher than the upper limit Comparative Example 12 1.83 1.21 0.649 0.21 0.083 0.0061 0.0031 4.68 0.661 0.0048 1.97 Aging temperature below the lower limit Comparative Example 13 1.83 1.21 0.649 0.21 0.083 0.0061 0.0031 4.68 0.661 0.0048 1.97 Aging temperature higher than the upper limit

[0046] Comparative Examples 1 to 11 were prepared according to the above preparation method, with a melting temperature of 1221℃, a casting temperature of 1197℃, a walking beam furnace temperature of 951℃, a heating time of 5.1 h, a solution temperature of 953℃, a water cooling method, an aging temperature of 501℃, a total rolling deformation of 30.7%, and an annealing temperature of 467℃. Comparative Examples 12 and 13 were identical to Comparative Examples 1 to 11 except for the aging temperature. The aging temperature of Comparative Example 12 was 380℃, and the aging temperature of Comparative Example 13 was 570℃.

[0047] The annealed copper alloy strips obtained from Examples 1 to 7 and Comparative Examples 1 to 13 were used as test samples to test their microstructure and properties. The test indicators and methods included:

[0048] Metallographic observation: Samples were taken along the rolling direction of the copper alloy strip. After grinding, polishing and etching, the metallographic structure was observed using a metallographic microscope at a magnification of 100x. The distribution of coarse second-phase particles, the aggregation state of the second phase near the grain boundaries and the uniformity of the structure were recorded.

[0049] The average grain size of the copper matrix was measured using the metallographic cross-section method. Samples were taken along the rolling direction of the copper alloy strip, and after grinding, polishing, and etching, measurements were taken under a metallographic microscope at five fields of view. Cross-sections were set along different directions, and the number of intersections between the cross-sections and grain boundaries was counted. The average grain intercept was calculated, and the arithmetic mean was taken as the average grain size of the copper matrix.

[0050] Conductivity was tested using an eddy current conductivity meter, and the test results were converted to %IACS. Three locations were tested for each sample and the arithmetic mean was taken.

[0051] Tensile strength was tested according to the room temperature tensile test method for metallic materials. Tensile specimens were prepared along the rolling direction of the copper alloy strip. Three specimens were tested for each group and the arithmetic mean was taken.

[0052] Thermal conductivity was tested using a laser thermal conductivity meter. Three samples were tested for each group. After obtaining the thermal diffusivity, the thermal conductivity was calculated by combining the sample density and specific heat capacity, and the arithmetic mean was taken.

[0053] The stress retention rate was evaluated according to the high temperature stress relaxation test method. The test conditions were 150℃ for 1000h and the applied stress was 0.2% of the yield strength (80%). After the heat preservation was completed, the residual stress was measured and the stress retention rate was calculated according to the ratio of the residual stress to the initial stress. Three samples were tested for each group and the arithmetic mean was taken.

[0054] The microstructure and properties of the copper alloy strips obtained in Examples 1 to 7 and Comparative Examples 1 to 13 were tested according to the above test methods. The test results are shown in Tables 4 and 5.

[0055] Table 4. Metallographic observation results of the examples and comparative examples

[0056] Group Distribution of coarse second phase in metallographic structure Second phase aggregation state near grain boundaries Average grain size of copper matrix / μm Example 1 The number is relatively small, and the distribution is basically discrete. No obvious continuous clustering was observed. 13.8 Example 2 Fewer, with a discrete distribution No obvious continuous clustering was observed. 11.6 Example 3 Fewer, with a discrete distribution No obvious continuous clustering was observed. 12.9 Example 4 Small quantity, discrete distribution No continuous clustering was observed. 9.4 Example 5 Fewer, with a discrete distribution No obvious continuous clustering was observed. 10.7 Example 6 Fewer, with a discrete distribution No continuous clustering was observed. 8.8 Example 7 Fewer, with a discrete distribution No obvious continuous clustering was observed. 9.7 Comparative Example 1 There are many, but they are unevenly distributed. Localized aggregations are visible near grain boundaries. 16.7 Comparative Example 2 There are many, but they are unevenly distributed. Localized aggregations are visible near grain boundaries. 15.8 Comparative Example 3 There are many, but they are unevenly distributed. Localized aggregations are visible near grain boundaries. 15.2 Comparative Example 4 There are many, but they are unevenly distributed. Localized aggregations are visible near grain boundaries. 13.6 Comparative Example 5 There are many, but they are unevenly distributed. Localized aggregations are visible near grain boundaries. 14.1 Comparative Example 6 Significantly more, unevenly distributed Aggregation is more pronounced near grain boundaries 15.9 Comparative Example 7 There are many, but they are unevenly distributed. Localized aggregations are visible near grain boundaries. 12.3 Comparative Example 8 There are many, but the distribution is uneven. Localized aggregations are visible near grain boundaries. 13.4 Comparative Example 9 There are many, but they are unevenly distributed. Localized aggregations are visible near grain boundaries. 12.7 Comparative Example 10 There are many, but they are unevenly distributed. Aggregation is more pronounced near grain boundaries 13.1 Comparative Example 11 There are many, but they are unevenly distributed. Localized aggregations are visible near grain boundaries. 12.5 Comparative Example 12 Insufficient organizational reinforcement features Aggregation is not obvious near grain boundaries 10.7 Comparative Example 13 The tissue is coarsened and unevenly distributed in some areas. Localized aggregations are visible near grain boundaries. 17.3

[0057] Table 5 Performance test results of the examples and comparative examples

[0058] Group Conductivity / %IACS Tensile strength / MPa Thermal conductivity / W / (m·K) Stress retention rate / % Example 1 51.6 821.7 195.8 82.4 Example 2 52.3 846.9 197.1 84.2 Example 3 51.8 856.4 194.6 85.9 Example 4 52.7 884.3 198.4 89.6 Example 5 50.9 902.8 193.7 86.8 Example 6 52.1 871.5 197.6 88.3 Example 7 51.4 895.6 195.2 87.7 Comparative Example 1 49.8 793.4 187.9 76.6 Comparative Example 2 55.1 724.6 205.3 73.8 Comparative Example 3 50.7 812.9 190.6 78.7 Comparative Example 4 50.9 824.5 192.3 80.4 Comparative Example 5 50.6 818.2 191.8 79.1 Comparative Example 6 51.2 829.7 193.6 80.8 Comparative Example 7 51.9 843.6 196.4 83.7 Comparative Example 8 48.6 836.8 186.5 77.9 Comparative Example 9 51.3 847.2 195.1 83.5 Comparative Example 10 51.1 839.8 194.3 82.6 Comparative Example 11 49.7 842.5 189.7 81.9 Comparative Example 12 48.9 752.6 187.8 78.4 Comparative Example 13 50.4 805.2 190.6 76.8

[0059] As shown in Tables 4 and 5, the conductivity of Examples 1 and 2 were 51.6% IACS and 52.3% IACS, respectively; the tensile strengths were 821.7 MPa and 846.9 MPa, respectively; and the stress retention rates were 82.4% and 84.2%, respectively. Comparative Example 1, a traditional Ni-Co-Si system, had a conductivity of 49.8% IACS, a tensile strength of 793.4 MPa, and a stress retention rate of 76.6%, all lower than Examples 1 and 2. Although Comparative Example 2 had a conductivity of 55.1% IACS, its tensile strength was only 724.6 MPa, and its stress retention rate was only 73.8%, indicating that while the low-Co system is beneficial for reducing the scattering of electron transport by solid solution atoms, its precipitation strengthening and high-temperature microstructure stability are insufficient. Comparative Example 3, using an Ag-strengthened route, had a conductivity of 50.7% IACS, a tensile strength of 812.9 MPa, and a stress retention rate of 78.7%, still lower than Examples 1 and 2. The above results demonstrate that the present invention, through the compatibility design of Ni, Co, Si, Zn, Sn, and Re, enables Ni, Co, and Si to form precipitation-strengthened structures during aging, reducing the content of residual solid solution atoms in the matrix. At the same time, Zn and Sn participate in regulating the solid solution state and thermal stability of the matrix, while Re, as a trace high-melting-point element, participates in the regulation of the microstructure and grain boundary state near the second phase. This improves the problem of traditional Ni-Co-Si copper alloys struggling to balance strength, electrical conductivity, and high-temperature stress retention.

[0060] Combine Table 4 and Figure 2 It can be seen that the metallographic structure of the copper alloy strip obtained in Example 2 is relatively uniform, with fewer coarse second-phase particles that are discretely distributed, and no obvious continuous aggregation regions are observed near the grain boundaries; in Comparative Example 1, there are relatively more coarse second-phase particles, and local aggregations are visible near the grain boundaries, indicating that the uniformity of the structure of the traditional Ni-Co-Si system is weaker than that of the basic alloy system of this invention.

[0061] Comparing Example 2 with Comparative Examples 4-6, it can be seen that, with essentially the same Ni, Co, and Si content, the absence of Zn, Sn, or Re leads to a decrease in microstructure and properties. Comparative Example 4 (no Zn added), Comparative Example 5 (no Sn added), and Comparative Example 6 (no Re added) exhibited weaker distribution of coarse second phases and less aggregation near grain boundaries compared to Example 2, with stress retention rates of 80.4%, 79.1%, and 80.8%, respectively. In contrast, Example 2 showed fewer coarse second phases with a discrete distribution and no obvious continuous aggregation near grain boundaries, resulting in a stress retention rate of 84.2%. This is because Zn and Sn, when introduced into the copper matrix at low concentrations, can regulate the matrix's solid solution state, recovery behavior, and microstructure changes near the second phase, reducing the tendency for uneven microstructure and local enrichment of coarse phases during aging and finished product annealing. Although the Re content is low, its high melting point and low diffusion rate allow it to hinder interface migration and limit the aggregation of coarse second phases near grain boundaries and the second phase.

[0062] The addition of boron (B) to the basic alloy system further improved the metallographic structure of the copper alloy strip. In Examples 3-7, the coarse second-phase particles were generally fewer and more dispersed, with no obvious continuous aggregation near the grain boundaries, and the average grain size of the copper matrix was 8.8 μm to 12.9 μm. Compared to Example 2 (without B), Example 4, with the addition of B to the same basic composition system, further reduced the coarse second-phase particles in the metallographic structure, resulting in a more dispersed distribution, no continuous aggregation near the grain boundaries, and a decrease in the average grain size of the copper matrix from 11.6 μm to 9.4 μm. Figure 3 It can be seen that the metallographic structure of the copper alloy strip obtained in Example 4 is relatively uniform with fewer coarse particles; while in Comparative Example 8, more obvious coarse particles and local enrichment areas are visible.

[0063] Examples 3 to 7 exhibited electrical conductivity of 50.9% IACS to 52.7% IACS, tensile strength of 856.4 MPa to 902.8 MPa, thermal conductivity of 193.7 W / (m·K) to 198.4 W / (m·K), and stress retention of 85.9% to 89.6%. Example 4 exhibited electrical conductivity of 52.7% IACS, tensile strength of 884.3 MPa, thermal conductivity of 198.4 W / (m·K), and stress retention of 89.6%, demonstrating superior overall performance. This performance improvement corresponds to its microstructure: on the one hand, Ni, Co, and Si form a precipitation strengthening base during aging, enhancing the copper alloy strip's resistance to dislocation movement; on the other hand, the combination of Zn, Sn, Re, and B helps improve the microstructure near grain boundaries and the second phase, resulting in a discrete distribution of identifiable coarse second-phase particles and reducing continuous network aggregation regions at grain boundaries. After the unevenness of the structure and the agglomeration of coarse particles are reduced, the risk of local stress concentration and crack initiation during high-temperature service is reduced, which helps to improve tensile strength and stress retention rate, while maintaining high electrical and thermal conductivity.

[0064] In Comparative Example 7, the B content was below the lower limit, resulting in a higher and more unevenly distributed coarse second phase in the metallographic structure. The stress retention rate was 83.7%, indicating that insufficient B content makes it difficult to adequately regulate the microstructure near grain boundaries and the second phase. In Comparative Example 8, the B content was above the upper limit, resulting in a higher and more unevenly distributed coarse second phase in the metallographic structure. The conductivity decreased to 48.6% IACS, and the stress retention rate decreased to 77.9%, indicating that excessive B content easily leads to local enrichment or promotes the formation of non-target coarse phases, thus disrupting the microstructure uniformity. In Comparative Example 9, the B:Si ratio was below the lower limit. In Comparative Examples 10 and 11, the Re:B ratio was below and above the limits defined in this invention, respectively. All of these examples showed varying degrees of increase in coarse second phases or aggregation near grain boundaries in their metallographic structures, with stress retention rates of 83.5%, 82.6%, and 81.9%, respectively.

[0065] In summary, this invention combines the basic components of Ni, Co, Si, Zn, Sn, and Re to achieve a Ni-Co-Si precipitation strengthening system with the microstructure stabilizing effects of low-content Zn, Sn, and Re. Without the addition of boron (B), it achieves a more balanced strength, electrical conductivity, thermal conductivity, and high-temperature stress retention compared to traditional Ni-Co-Si, low-Co, and Ag-strengthened systems. Furthermore, by adding B and controlling the B:Si and Re:B ratios, the regulatory effect of B on the microstructure near grain boundaries and the second phase complements the interfacial stabilizing effect of Re, thereby improving the uniformity of the metallographic structure, reducing the continuous network of second phase aggregation regions at grain boundaries, and dispersing identifiable coarse second phase particles. This copper alloy strip can meet the comprehensive requirements of AI computing center connection, conductive, and heat dissipation components for high strength, high electrical conductivity, high thermal conductivity, and long-term thermal stability.

[0066] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A high-strength, high-temperature-resistant copper alloy strip, characterized by, By mass percentage, it includes Ni 0.6%–3.8%, Co 0.9%–1.6%, Si 0.35%–0.85%, Zn 0.03%–0.45%, Sn 0.02%–0.18%, Re 0.001%–0.02%, with the balance being Cu and unavoidable impurities.

2. The high-strength, high-temperature resistant copper alloy strip of claim 1, wherein, By mass percentage, it includes Ni 1%–3%, Co 1.1%–1.3%, Si 0.55%–0.65%, Zn 0.1%–0.3%, Sn 0.05%–0.1%, Re 0.005%–0.01%, with the balance being Cu and unavoidable impurities.

3. The high-strength, high-temperature resistant copper alloy strip of claim 1 or 2, wherein, The total content of Ni and Co is in a mass ratio of 3.9:1 to 4.7:1 to Si, and the mass ratio of Co to Ni is 0.37:1 to 1.30:

1.

4. The high-strength, high-temperature resistant copper alloy strip of claim 1 or 2, wherein, It also includes 0.0005% to 0.01% B, wherein the mass ratio of B to Si is 0.001:1 to 0.018:1, and the mass ratio of Re to B is 0.8:1 to 20:

1.

5. The high-strength, high-temperature resistant copper alloy strip of claim 4, wherein, In the metallographic structure of the copper alloy strip, coarse second-phase particles can be identified as being discretely distributed, and no continuous network of second-phase aggregate regions are formed at the grain boundaries. The average grain size of the copper matrix in the copper alloy strip is 4μm to 15μm.

6. The high-strength, high-temperature resistant copper alloy strip of claim 5, wherein, The copper alloy strip has an electrical conductivity of not less than 50% IACS, a tensile strength of not less than 850MPa, a thermal conductivity of not less than 192W / (m·K), and a stress retention rate of not less than 85% under the conditions of 150℃, 1000h, and a loading stress of 0.2% of the yield strength.

7. The method of producing a high-strength high-temperature-resistant copper alloy strip according to any one of claims 4 to 6, characterized in that, Includes the following steps: S1. Provide Cu source, Ni source, Co source, Si source, Zn source, Sn source, Re source and B source according to the ratio, melt and cast in a melting furnace to obtain ingot or billet; S2. The ingot or billet is heated in a walking beam furnace and then hot rolled to obtain a hot rolled billet. The hot rolled billet is then subjected to milling, rough rolling and solution treatment and then cooled to obtain a solution-treated billet. S3. The solution-treated billet is subjected to cold rolling, aging treatment, finished product rolling and finished product annealing to obtain the copper alloy strip.

8. The method of producing a high-strength high-temperature-resistant copper alloy strip according to claim 7, characterized by, In step S1, the B source is a Cu-B master alloy, the melting temperature is 1100℃~1300℃, and the casting temperature is 1100℃~1300℃; in step S2, the walking beam furnace heating temperature is 900℃~1000℃, the heating time is 3h~6h, the hot rolling start temperature is 900℃~1000℃, and the hot rolling end temperature is above 600℃.

9. The method of producing a high-strength high-temperature-resistant copper alloy strip according to claim 7, characterized by, In step S2, the milling amount is 0.3mm to 1mm per surface and 1mm to 3mm per side surface. The solution treatment temperature is 900℃ to 1000℃. After solution treatment, the product is cooled by air cooling, water cooling, or mist cooling. In step S3, the aging temperature is 400℃ to 550℃, the total deformation of the finished product during rolling is 10% to 50%, and the annealing temperature of the finished product is 350℃ to 550℃.

10. The application of a high-strength, high-temperature resistant copper alloy strip as described in any one of claims 1-6 in an AI computing center.

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