High-performance copper-aluminum composite bar with large width-to-thickness ratio and preparation method thereof

Abstract

The invention relates to the technical field of composite materials, in particular to a high-performance large-width-to-thickness-ratio copper-aluminum composite bar and a preparation method thereof.The high-performance large-width-to-thickness-ratio copper-aluminum composite bar comprises a coated copper layer and an aluminum core base body, and a bonding layer for atomic bonding is formed between the coated copper layer and the aluminum core base body. According to the copper-aluminum composite conducting bar with the high tensile strength, the high bonding strength and the high conductivity, copper and aluminum are bonded in a metallurgical bonding state, the thickness of a bonding layer is smaller than 3 microns, the shear bonding strength is larger than or equal to 100 MPa, the copper containing volume ratio is 18%-32%, the tensile strength is 195-255 MPa, the ductility is larger than or equal to 25%, and the volume conductivity is larger than or equal to 71.5% IACS; when the width of the product is larger than or equal to 80 mm, the minimum thickness can reach 2 mm; when the width of the product is 50-60 mm, the minimum thickness can be 1.5 mm; and when the width of the product is less than or equal to 40mm, the minimum thickness can reach 1mm.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a high-performance large width-to-thickness ratio copper-aluminum composite bar and a preparation method thereof. Background Art

[0002] Copper-aluminum composite busbar is a composite conductor material with copper as the outer layer and aluminum as the core. It is formed into a layered composite material through a special process. Compared with copper busbar, it has the advantages of reducing weight and cost, and compared with aluminum busbar, it has the advantages of low contact resistance and good creep resistance. According to the structure, based on the aluminum substrate, copper-aluminum composite materials include partial copper cladding, single-sided copper cladding, double-sided copper cladding, and full copper cladding on the sides. According to the preparation process, there are solid-solid welding, solid-solid crimping (hydrostatic extrusion, rolling, drawing, forging, etc.), solid-liquid composite (casting and rolling method), and liquid-liquid composite (continuous casting composite method). Among them, the copper-aluminum composite products that combine performance to meet the market's demand for mass use mainly include GB / T 30586-2022 "Copper Clad Aluminum Flat Bar" and GB / T 32468-2015 "Copper Clad Aluminum Composite Plate and Strip". The corresponding preparation processes are continuous casting composite method and cast-rolling method. The continuous casting composite copper-aluminum composite bar is a structural type with fully copper-covered sides, with better structural integrity. When used in the power and electrical field, it can better match subsequent bending, processing, and electroplating requirements, and has better current-carrying effect and corrosion resistance.

[0003] For the copper-aluminum composite busbar with full copper cladding on the sides, the GB / T 30586 product disclosed in China's invention patent 201611114257.5, a high bonding strength copper-aluminum composite conductive material and its preparation method, has a bonding layer thickness of 5~35μm, a shear bonding strength ≥45MPa, a tensile strength of 100~130MPa, an elongation ≥25%, and a volume conductivity ≥71.1%IACS. Combined with the process disclosed in China's invention patent 201010225901.2, a preparation process for copper-clad aluminum composite busbar, and China's invention patent 201310304077.3, a hole rolling process for copper-clad aluminum busbar, after continuous casting, rolling, and drawing, when the width of the GB / T 30586 product is ≥80mm, the minimum thickness can be 6mm; when the product width is 50~60mm, the minimum thickness can be 5mm; when the product width is ≤40mm, the minimum thickness can be 4mm.

[0004] Since thinner products have higher current density, better cost performance and better weight reduction effect, in the actual selection process, more and more power and electrical design manufacturers tend to choose products with a large width and small thickness to reduce weight and cost; and due to the requirements of high-end manufacturing fields such as aerospace, rail transit, new energy vehicles, and power equipment, higher requirements are placed on key mechanical properties and electrical performance indicators such as bonding strength, tensile strength, conductivity, and processing performance of copper-aluminum composite bars. It is difficult for existing technical products to meet the usage requirements.

[0005] For products with thin dimensions and large width and thickness ratio, when they are prepared through the existing public continuous rolling or drawing process, problems such as product edge cracking, flat orange peel, and cracking are prone to occur; and problems such as cracking are prone to occur during longitudinal bending (along the rolling processing direction); the above problems are more prominent when the strength of the aluminum core material is higher, and it is difficult to meet the current market demand. Summary of the invention

[0006] In view of the above deficiencies in the prior art, the object of the present invention is to provide a high-performance large width-to-thickness ratio copper-aluminum composite bar and a preparation method thereof.

[0007] To achieve the above objectives, the technical solutions adopted are: One of the purposes of the present invention is to provide a high-performance copper-aluminum composite bar with a large width-to-thickness ratio, comprising a cladding copper layer and an aluminum core substrate, i.e., a copper-clad aluminum structure, wherein an atomically bonded bonding layer is formed between the cladding copper layer and the aluminum core substrate, and the thickness of the bonding layer is less than 3 μm. When the width of the high-performance copper-aluminum composite bar with a large width-to-thickness ratio is ≥80 mm, the width-to-thickness ratio is 20-60; when the width is 50-60 mm, the width-to-thickness ratio is 20-40; when the width is ≤40 mm, the width-to-thickness ratio is 10-40.

[0008] Furthermore, the aluminum core matrix includes aluminum, silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials, and the rare earth alloy materials include cerium, lanthanum, neodymium and praseodymium.

[0009] Furthermore, the mass fractions of silicon, iron, copper, magnesium, zinc and boron in aluminum are as follows: silicon 0.03%~0.07%, iron 0.40%~0.60%, copper 0.20%~0.40%, magnesium 0.04%~0.10%, zinc 0.04%~0.10%, and boron 0.01%~0.02%; the mass fractions of cerium, lanthanum, neodymium and praseodymium in aluminum are as follows: cerium 0.06%~0.09%, lanthanum 0.01%~0.03%, neodymium 0.01%~0.03%, and praseodymium 0.007%~0.015%.

[0010] One of the purposes of the present invention is to provide a method for preparing the high-performance large width-to-thickness ratio copper-aluminum composite bar, comprising the following steps: (1) Continuous casting composite The electrolytic copper plate is melted into copper liquid, and then covered with charcoal and kept at 1150~1250℃ for 3~6h; After the electrolytic aluminum ingot is melted, alloy materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials cerium, lanthanum, neodymium and praseodymium are added in sequence, wherein the mass fractions of silicon, iron, copper, magnesium, zinc and boron in aluminum are as follows: silicon 0.03% to 0.07%, iron 0.40% to 0.60%, copper 0.20% to 0.40%, magnesium 0.04% to 0.10%, zinc 0.04% to 0.10%, and boron 0.01% to 0.02%; the mass fractions of cerium, lanthanum, neodymium and praseodymium in aluminum are as follows: cerium 0.06% to 0.09%, lanthanum 0.01% to 0.03%, neodymium 0.01% to 0.03%, and praseodymium 0.007% to 0.015%. Heat preservation at 750 to 850°C, degassing and slagging twice, to obtain aluminum liquid; The copper liquid and the aluminum liquid are respectively charged into the composite furnace through different channels, and the copper-aluminum continuous casting is directly composited to prepare the copper-aluminum composite rod blank, and the square rod blank with a side length of 60-150 mm is obtained, and the thickness of the rod blank bonding layer is 5-15 μm; (2) Rolling copper-aluminum composite bar billet Through a two-roll reversible rolling mill, the pass is reciprocated and rolled, and flat rolling and vertical rolling are performed alternately, that is, the first, third, fifth, seventh and ninth passes (subsequent passes are added according to actual needs) are flat rolling, and the second, fourth, sixth and eighth passes are vertical rolling (subsequent passes are added according to actual needs); the thickness of the copper-aluminum composite bar after rolling is 10~14mm, and the width after rolling is 0.5~2.5mm larger than the width of the final product; (3) Process drawing and intermediate heat treatment The incoming material continues to be drawn or coiled, the thickness reduction of the first drawing is 20%~35%, and the thickness reduction of the subsequent drawing is 10%~30%; the width reduction is 0.05~1.0mm per pass, and the process drawing is to a thickness of 3.0~5.5mm; then the first intermediate heat treatment is carried out; continue to draw multiple times to the last process drawing size before the finished product specification, the process drawing size is 0.2~0.8mm larger than the final product thickness, and 0.05~0.3mm larger than the final product width; then the second intermediate heat treatment is carried out; (4) Finished product drawing and finished product heat treatment Finished product drawing, when the product width is ≥80mm, the minimum thickness can reach 2mm; when the product width is 50~60mm, the minimum thickness can reach 1.5mm; when the product width is ≤40mm, the minimum thickness can reach 1mm; finished product heat treatment, the thickness of the finished product bonding layer is less than 3μm; shear bonding strength ≥100MPa, copper volume ratio 18%~32%, tensile strength 195~255MPa, elongation ≥25%, volume conductivity ≥71.5%IACS; (5) Surface treatment Use 180~240 mesh sanding belt to perform surface grinding and brushing 1~2 groups, each group of grinding includes two grindings.

[0011] Furthermore, in step (2), the thickness reduction of the first pass of flat rolling is 35% to 60%, the thickness reduction of each pass of the remaining flat rolling is controlled between 10% and 35%, the thickness reduction of each pass of vertical rolling is controlled between 3% and 20%, and the total number of rolling passes is 10 to 25.

[0012] The beneficial effects of adopting the above technical solution are: if the amount of reduction during the rolling process is not appropriate, the final rolling size cannot be achieved, or too many passes are required to achieve it, resulting in an increase in the number of required rolls and increased costs; if the amount of reduction during the drawing process is not appropriate, it will cause problems such as edge cracking or flat orange peel, cracking, etc., and the product will be scrapped and cannot be used any further.

[0013] Furthermore, in step (3), the first intermediate heat treatment is carried out at 185-205°C for 1-2 hours; and the second intermediate heat treatment is carried out at 165-185°C for 1-2 hours.

[0014] Furthermore, the finished product in step (4) is heat treated at 230-255° C. for 0.5-1.5 h.

[0015] Furthermore, in step (5), the angles between the sanding belt and the product length direction during the two grinding steps are 30-60° and 120-150° respectively.

[0016] The beneficial effect of adopting the above-mentioned further technical solution is that the polished wire drawing pattern has an angle with the rolling and drawing processing direction, which weakens the adverse effect of the texture on bending in the specified direction, takes into account the connection contact resistance and bending processing performance, improves the radiation heat dissipation coefficient, enhances the current carrying capacity, and improves the adhesion of the subsequent coating.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention discloses a copper-aluminum composite bar with high tensile strength, high bonding strength, high conductivity, ultra-thinness and large aspect ratio; (2) The present invention adopts a rare earth aluminum alloy formula to achieve high tensile strength and high conductivity of the copper-aluminum composite bar, and through the subsequent process drawing and intermediate heat treatment process, the negative impact of the high strength of the core material and the alloy elements on the processing and bonding strength of the ultra-thin material is eliminated; (3) The present invention achieves a thinner bonding layer thickness through comprehensive regulation of rolling, drawing processing, and multiple heat treatments, thereby achieving high bonding strength of the copper-aluminum composite bar; (4) The present invention meets various bending requirements such as transverse bending, longitudinal bending, side bending, twist bending, etc., and improves the adhesion of the coating; (5) The present invention does not require the use of expensive and complex continuous rolling mills, but only uses an existing two-roll rolling mill and part of the transition drawing die, thereby realizing the rapid preparation of ultra-thin copper-aluminum composite bars with a large aspect ratio at a low cost.

[0018] The copper-aluminum composite conductive bar with high tensile strength, high bonding strength and high conductivity of the present invention has a metallurgical bonding state between copper and aluminum, a bonding layer thickness of less than 3μm, a shear bonding strength of ≥100MPa, a copper volume ratio of 18% to 32%, a tensile strength of 195 to 255MPa, an elongation of ≥25%, and a volume conductivity of ≥71.5%IACS. When the product width is ≥80mm, the minimum thickness can be 2mm; when the product width is 50 to 60mm, the minimum thickness can be 1.5mm; when the product width is ≤40mm, the minimum thickness can be 1mm. DETAILED DESCRIPTION

[0019] The present invention is described below in conjunction with examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0020] Example 1 Copper-aluminum composite bar product specifications: width 120mm, thickness 2mm: 1. Continuous casting composite The electrolytic copper plate is melted into copper liquid, covered with charcoal and kept at 1200~1250℃ for 4 hours.

[0021] After the electrolytic aluminum ingot is melted, alloy materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials cerium, lanthanum, neodymium and praseodymium are added in sequence. The mass fractions of silicon, iron, copper, magnesium, zinc, neodymium and praseodymium in aluminum are respectively: silicon 0.055%, iron 0.500%, copper 0.220%, magnesium 0.045%, zinc 0.045% and boron 0.015%; the rare earth materials include the following weight ratios of elements: cerium 0.070%, lanthanum 0.015%, neodymium 0.015% and praseodymium 0.010%. The aluminum liquid is obtained by heat preservation at 780-830℃, degassing and slagging twice.

[0022] The copper liquid and the aluminum liquid are respectively charged into the composite furnace through different channels for direct composite forming of copper-aluminum continuous casting to prepare copper-aluminum composite rod billets. The square rod billets have a side length of 135 mm and a bonding layer thickness of 5 to 10 μm.

[0023] 2. Rolling copper-aluminum composite bar billet Through a two-roll reversible rolling mill, the groove type is reciprocated and flat rolling and vertical rolling are performed alternately, that is, the first, third, fifth, seventh and ninth odd-numbered passes are flat rolling, and the second, fourth, sixth and eighth even-numbered passes are vertical rolling. The first pass of the billet flat rolling has a reduction of 45%, and the remaining flat rolling reductions are 30% for the third pass, 27% for the fifth pass, 26% for the seventh pass, 25% for the ninth pass, 24% for the eleventh pass, and 19% for the thirteenth pass; the vertical rolling reductions are 10% for the second pass, 9% for the fourth pass, 9% for the sixth pass, 8% for the eighth pass, 5% for the tenth pass, and 5% for the twelfth pass; the copper-aluminum composite bar has a thickness of 13.00mm and a width of 121.60mm after rolling; 3. Process drawing and intermediate heat treatment The incoming material continues to be drawn or coiled. The first drawing process has a thickness reduction of 23% and a width reduction of 0.55mm. The second drawing process has a thickness reduction of 22% and a width reduction of 0.20mm. The third drawing process has a thickness reduction of 21% and a width reduction of 0.15mm. The fourth drawing process has a thickness reduction of 19% and a width reduction of 0.15mm. At this time, the process drawing thickness is 5.00mm and the width is 120.55mm. The first intermediate heat treatment is carried out at 195℃ for 1.5h. Continue The fifth drawing pass has a thickness reduction of 24% and a width reduction of 0.20mm, the sixth drawing pass has a thickness reduction of 18% and a width reduction of 0.10mm, and the seventh drawing pass has a thickness reduction of 11% and a width reduction of 0.10mm. At this time, the last drawing dimension before the finished product specification is 2.60mm thick and 120.15mm wide, which is 0.60mm thicker than the final finished product and 0.15mm wider than the final finished product; then the second intermediate heat treatment is carried out, and the temperature is kept at 170℃ for 1.5h; 4. Finished product drawing and finished product heat treatment The finished product is drawn with a thickness reduction of 23% and a width reduction of 0.15mm. At this time, the product width is 120mm and the thickness is 2mm. The finished product is heat treated at 240℃ for 1h. The thickness of the finished product bonding layer is 0.50~1.50μm, the shear bonding strength is 115MPa, the copper volume ratio is 25%, the tensile strength is 215MPa, the elongation is 27%, and the volume conductivity is ≥71.9%IACS.

[0024] 5. Surface treatment Use 230 mesh abrasive belt to perform surface grinding and drawing for 1 group. Each group of grinding includes two grindings. The angles between the two grinding belts and the length direction of the product are 40° and 130° respectively. The grinding and drawing lines have an angle with the rolling and drawing processing direction, which weakens the adverse effect of the texture on bending in the specified direction, takes into account the connection contact resistance and bending processing performance, improves the radiation heat dissipation coefficient, enhances the current carrying capacity, and improves the adhesion of the subsequent coating.

[0025] Example 2 Copper-aluminum composite bar product specifications: width 50mm, thickness 1.5mm: 1. Continuous casting composite The electrolytic copper plate is melted into copper liquid, covered with charcoal and kept at 1200~1250℃ for 4 hours.

[0026] After the electrolytic aluminum ingot is melted, alloy materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials cerium, lanthanum, neodymium and praseodymium are added in sequence. The mass fractions of silicon, iron, copper, magnesium, zinc, neodymium and praseodymium in aluminum are respectively: silicon 0.060%, iron 0.450%, copper 0.210%, magnesium 0.047%, zinc 0.045%, and boron 0.017%; the rare earth materials include the following weight ratios of elements: cerium 0.080%, lanthanum 0.020%, neodymium 0.020%, and praseodymium 0.012%. The aluminum liquid is obtained by heat preservation at 780-830℃, degassing and slagging twice.

[0027] The copper liquid and the aluminum liquid are respectively charged into the composite furnace through different channels for direct composite forming of copper-aluminum continuous casting to prepare copper-aluminum composite rod billets. The square rod billets have a side length of 110 mm and a bonding layer thickness of 5 to 10 μm.

[0028] 2. Rolling copper-aluminum composite bar billet Through a two-roll reversible rolling mill, the groove type is reciprocated and flat rolling and vertical rolling are performed alternately, that is, the first, third, fifth, seventh and ninth odd-numbered passes are flat rolling, and the second, fourth, sixth and eighth even-numbered passes are vertical rolling. The first pass of flat rolling has a reduction of 37%, and the remaining flat rolling reductions are 23% for the third pass, 23% for the fifth pass, 23% for the seventh pass, 22% for the ninth pass, 20% for the eleventh pass, 20% for the thirteenth pass, and 20% for the fifteenth pass; the vertical rolling reductions are 19% for the second pass, 19% for the fourth pass, 19% for the sixth pass, 18% for the eighth pass, 10% for the tenth pass, 4% for the twelfth pass, and 4% for the fourteenth pass; the copper-aluminum composite bar has a thickness of 12.90mm and a width of 51.30mm after rolling; 3. Process drawing and intermediate heat treatment The incoming material continues to be drawn or coiled. The first drawing process has a thickness reduction of 27% and a width reduction of 0.30mm. The second drawing process has a thickness reduction of 24% and a width reduction of 0.19mm. The third drawing process has a thickness reduction of 24% and a width reduction of 0.15mm. The fourth drawing process has a thickness reduction of 23% and a width reduction of 0.11mm. At this time, the process drawing thickness is 4.20mm and the width is 50.55mm. The first intermediate heat treatment is carried out at 192℃ for 1.5h. Continue The fifth drawing pass has a thickness reduction of 25% and a width reduction of 0.19mm, the sixth drawing pass has a thickness reduction of 22% and a width reduction of 0.11mm, and the seventh drawing pass has a thickness reduction of 20% and a width reduction of 0.11mm. At this time, the last drawing dimension before the finished product specification is 1.95mm thick and 50.14mm wide, which is 0.45mm thicker than the final finished product and 0.14mm wider than the final finished product; then the second intermediate heat treatment is carried out, and the temperature is kept at 168℃ for 1.5h; 4. Finished product drawing and finished product heat treatment The finished product is drawn with a thickness reduction of 23% and a width reduction of 0.14mm. At this time, the product width is 50mm and the thickness is 1.50mm. The finished product is heat treated at 237℃ for 1h. The thickness of the finished product bonding layer is 0.30~1.20μm, the shear bonding strength is 119MPa, the copper volume ratio is 25%, the tensile strength is 222MPa, the elongation is 28%, and the volume conductivity is ≥72.3%IACS.

[0029] 5. Surface treatment Use 230 mesh abrasive belt to perform surface grinding and brushing for 1 group. Each group of grinding includes two grindings. The angles between the two grinding belts and the length direction of the product are 45° and 135° respectively.

[0030] Example 3 Copper-aluminum composite bar product specifications: width 30mm, thickness 1mm: 1. Continuous casting composite The electrolytic copper plate is melted into copper liquid, covered with charcoal and kept at 1200~1250℃ for 4 hours.

[0031] After the electrolytic aluminum ingot is melted, alloy materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials cerium, lanthanum, neodymium and praseodymium are added in sequence. The mass fractions of silicon, iron, copper, magnesium, zinc, zinc and praseodymium are respectively: silicon 0.065%, iron 0.550%, copper 0.220%, magnesium 0.042%, zinc 0.045% and boron 0.015%; the rare earth materials include the following weight ratios of elements: cerium 0.070%, lanthanum 0.022%, neodymium 0.017% and praseodymium 0.013%. The aluminum liquid is obtained by heat preservation at 780-830℃, degassing and slagging twice.

[0032] The copper liquid and the aluminum liquid are respectively charged into the composite furnace through different channels for direct composite forming of copper-aluminum continuous casting to prepare copper-aluminum composite rod billets, which are square rod billets with a side length of 75 mm and a bonding layer thickness of 5-10 μm.

[0033] 2. Rolling copper-aluminum composite bar billet Through a two-roll reversible rolling mill, the groove type is reciprocated and flat rolling and vertical rolling are carried out alternately, that is, the first, third, fifth, seventh and ninth odd-numbered passes are flat rolling, and the second, fourth, sixth and eighth even-numbered passes are vertical rolling. The first pass of the billet flat rolling has a reduction of 41%, and the remaining flat rolling reductions are 22% for the third pass, 20% for the fifth pass, 18% for the seventh pass, 18% for the ninth pass, 17% for the eleventh pass, 16% for the thirteenth pass, 15% for the fifteenth pass, and 14% for the seventeenth pass; the vertical rolling reductions are 19% for the second pass, 18% for the fourth pass, 18% for the sixth pass, 17% for the eighth pass, 14% for the tenth pass, 10% for the twelfth pass, 7% for the fourteenth pass, and 7% for the sixteenth pass; the copper-aluminum composite bar has a thickness of 10.40mm and a width of 31.10mm after rolling; 3. Process drawing and intermediate heat treatment The incoming material continues to be drawn or coiled. The first drawing process has a thickness reduction of 31% and a width reduction of 0.25mm. The second drawing process has a thickness reduction of 25% and a width reduction of 0.15mm. The third drawing process has a thickness reduction of 25% and a width reduction of 0.10mm. The fourth drawing process has a thickness reduction of 24% and a width reduction of 0.10mm. At this time, the process drawing thickness is 3.10mm and the width is 30.50mm. The first intermediate heat treatment is carried out, and the temperature is kept at 190℃ for 1.5h. Continue The fifth drawing pass has a thickness reduction of 27% and a width reduction of 0.15mm, the sixth drawing pass has a thickness reduction of 25% and a width reduction of 0.12mm, and the seventh drawing pass has a thickness reduction of 23% and a width reduction of 0.11mm. At this time, the last drawing dimension before the finished product specification is 1.32mm thick and 30.12mm wide, which is 0.32mm thicker than the final finished product and 0.12mm wider than the final finished product; then the second intermediate heat treatment is carried out, and the temperature is kept at 166℃ for 1.5h; 4. Finished product drawing and finished product heat treatment The finished product is drawn with a thickness reduction of 24% and a width reduction of 0.12mm. At this time, the product width is 30mm and the thickness is 1.0mm. The finished product is heat treated at 235℃ for 1h. The thickness of the finished product bonding layer is 0.20~0.90μm, the shear bonding strength is 124MPa, the copper volume ratio is 25%, the tensile strength is 231MPa, the elongation is 29%, and the volume conductivity is ≥72.7%IACS.

[0034] 5. Surface treatment Use 230 mesh abrasive belt to perform surface grinding and brushing for 1 group. Each group of grinding includes two grindings. The angles between the grinding belt and the length direction of the product are 50° and 140° respectively.

[0035] Comparative Example 1 The difference from Example 1 is that the first intermediate heat treatment is not performed, and during the fifth drawing, the product surface becomes orange peel or even the copper layer cracks, and the product becomes scrapped and cannot be used any further.

[0036] Comparative Example 2 The difference from Example 2 is that the finished product is heat treated at a temperature of 295° C. and kept warm for 2 hours, and the tensile strength of the obtained product is 185 MPa, and the tensile strength performance is unqualified.

[0037] Comparative Example 3 The difference from Example 3 is that after the electrolytic aluminum ingot is melted, alloy materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials cerium, lanthanum, neodymium and praseodymium are added in sequence. Silicon 0.020%, iron 0.250%, copper 0.040%, magnesium 0.030%, zinc 0.040%, boron 0.010%; the rare earth materials include the following weight ratios of elements: cerium 0.020%, lanthanum 0.008%, neodymium 0.007%, praseodymium 0.005%. The tensile strength of the obtained product is 165MPa, and the tensile strength performance is unqualified.

[0038] Comparative Example 4 The difference from Example 1 is that the aluminum liquid does not contain rare earth elements, that is, after the electrolytic aluminum ingot is melted, alloy materials silicon, iron, copper, magnesium, zinc, and boron are added in sequence, with the contents of: silicon 0.055%, iron 0.500%, copper 0.220%, magnesium 0.045%, zinc 0.045%, and boron 0.015%. The volume conductivity of the obtained product is ≥70.3%IACS, and the volume conductivity performance is unqualified.

[0039] Comparative Example 5 The difference from Example 2 is that the finished product is heat treated at a temperature of 330°C and kept warm for 5 hours. The obtained product has a tensile strength of 165 MPa, a bonding layer thickness of 8 μm, and an interface bonding strength of 65 MPa. The above three indicators are all unqualified.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-performance copper-aluminum composite bar with a large width-to-thickness ratio, characterized in that: It comprises a clad copper layer and an aluminum core substrate, wherein a bonding layer is formed between the clad copper layer and the aluminum core substrate, and the thickness of the bonding layer is less than 3 μm. When the width of the high-performance large aspect ratio copper-aluminum composite bar is ≥80 mm, the aspect ratio is 20-60; when the width is 50-60 mm, the aspect ratio is 20-40; when the width is ≤40 mm, the aspect ratio is 10-40.

2. The high-performance copper-aluminum composite bar with a large width-to-thickness ratio according to claim 1 is characterized in that: The aluminum core matrix includes aluminum, silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials, and the rare earth alloy materials include cerium, lanthanum, neodymium and praseodymium.

3. The high performance copper-aluminum composite bar with large width-to-thickness ratio according to claim 2 is characterized in that: The mass fractions of silicon, iron, copper, magnesium, zinc and boron in aluminum are as follows: silicon 0.03%~0.07%, iron 0.40%~0.60%, copper 0.20%~0.40%, magnesium 0.04%~0.10%, zinc 0.04%~0.10%, and boron 0.01%~0.02%; the mass fractions of cerium, lanthanum, neodymium and praseodymium in aluminum are as follows: cerium 0.06%~0.09%, lanthanum 0.01%~0.03%, neodymium 0.01%~0.03%, and praseodymium 0.007%~0.015%.

4. A method for preparing a high-performance copper-aluminum composite bar with a large width-to-thickness ratio as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Continuous casting composite The electrolytic copper plate is melted into copper liquid and kept at 1150~1250℃ for 3~6h; After the electrolytic aluminum ingot is melted, alloy materials silicon, iron, copper, magnesium, zinc, boron and rare earth alloy materials cerium, lanthanum, neodymium and praseodymium are added in sequence, and the temperature is kept at 750-850℃, and degassing and slagging are performed twice to obtain aluminum liquid; The copper liquid and the aluminum liquid are respectively charged into the composite furnace through different channels, and the copper-aluminum continuous casting is directly composited to prepare the copper-aluminum composite rod blank, and the thickness of the bonding layer of the rod blank is 5-15μm; (2) Rolling copper-aluminum composite bar billet Through a two-roller reversible rolling mill, the groove is reciprocated and rolled, and the flat rolling and vertical rolling are performed alternately. The thickness of the copper-aluminum composite bar after rolling is 10~14mm, and the width after rolling is 0.5~2.5mm larger than the width of the final product; (3) Process drawing and intermediate heat treatment Drawing is performed, the thickness reduction of the first drawing is 20%~35%, and the thickness reduction of the subsequent drawing is 10%~30%; the width reduction is 0.05~1.0mm per pass, and the process drawing is to a thickness of 3.0~5.5mm; then the first intermediate heat treatment is performed; multiple drawing is continued to the last process drawing size before the finished product specification, and the process drawing size is 0.2~0.8mm larger than the final product thickness and 0.05~0.3mm larger than the final product width; then the second intermediate heat treatment is performed; (4) Finished product drawing and finished product heat treatment Finished product drawing, when the product width is ≥80mm, the minimum thickness can reach 2mm; when the product width is 50~60mm, the minimum thickness can reach 1.5mm; when the product width is ≤40mm, the minimum thickness can reach 1mm; finished product heat treatment, the thickness of the finished product bonding layer is less than 3μm; (5) Surface treatment Use a sanding belt to perform surface grinding and brushing 1 to 2 times, each set of grinding includes two times of grinding.

5. The method for preparing a high-performance copper-aluminum composite bar with a large width-to-thickness ratio according to claim 4, characterized in that: In step (2), the thickness reduction of the first flat rolling is 35% to 60%, the thickness reduction of each remaining flat rolling is controlled between 10% and 35%, and the thickness reduction of each vertical rolling is controlled between 3% and 20%.