铜包铝丝材的旋锻复合-拉拔成形与组织性能

Rotary swaging-drawing formation, microstructure, and properties of copper-clad aluminum composite micro-wires

  • 摘要: 采用"热旋锻-拉拔"方法制备了直径为φ65 μm、包覆铜层厚度较均匀、表面质量高和界面结合质量良好的铜包铝复合微丝,研究了合理热旋制度、热旋复合成形铜包铝线材的组织和界面结合状态以及中间退火和拉拔对线材组织与性能的影响.结果表明:合理的旋锻制度为旋锻温度350℃,单道次变形量40%,旋锻后形成了动态再结晶组织和厚度为0.7 μm的界面扩散层.复合线材的合理退火工艺参数为350℃/30 min (退火温度350℃、退火时间30 min),该条件下退火后线材延伸率达到最高值35.7%,界面扩散层厚度约为2.1 μm,退火后铜层和铝芯发生再结晶,组织内部形成等轴晶组织.当退火温度超过350℃时,铜层和铝芯晶粒长大,界面扩散层厚度增加,从而导致线材的延伸率下降.将单道次变形量控制在15%~20%,经过粗拉,制备了φ0.96 mm的丝材;粗拉后不进行退火处理,将单道次变形量控制在8%~15%,经过细拉,制备了表面光洁、直径为φ65 μm的复合微丝.在拉拔过程中,铜层和铝芯均出现〈111〉丝织构.

     

    Abstract: Copper-clad aluminum wires are extensively applied in aerospace, telecommunications, national defense industry, and other fields, because of the combined advantages of the excellent conductivity, thermal conductivity, and low contact resistance of copper and the low density, corrosion resistance, and low costs of aluminum. In this study, a composite wire with high interfacial bonding quality was obtained by hot rotary swaging, which can be utilized in manufacturing to achieve high efficiency and high quality because of its feature of the large single-pass deformation. The processed wire was then prepared by drawing into micro-wires, and given this, a simple, inexpensive, and highly efficient method for preparing micro-wires was developed in this study. Copper-clad aluminum wires with a diameter of φ65 μm, uniformly thick coating, glossy surface, and good interfacial bonding were prepared by the hot rotary swaging-drawing method. The rotary swaging parameters and the microstructure and interfacial bonding of the composite wire were studied, and the effects of drawing and intermediate annealing on its microstructure and properties were discussed. The results show that the reasonable swaging parameters are 350℃ swaging temperature with 40% single-pass deformation. After the rotary swaging, dynamic recrystallization microstructures and interface diffusion layer with thickness of 0.7 μm are formed. The optimum annealing parameter is 350℃/30 min (350℃ annealing temperature with 30 min annealing time), under which the elongation reaches 35.7%, the thickness of interface diffusion layer is 2.1 μm, and the copper layer and the aluminum core are recrystallized with the formation of equiaxed grains. When the annealing temperature exceeds 350℃, copper and aluminum grains and the interface layer thickness increase, which will lead to a lower wire elongation. A wire of φ0.96 mm is fabricated by a 15%-20% single-pass deformation, and then the φ65 μm diameter wire is manufactured by an 8%-15% single-pass deformation without annealing. In the drawing process, 〈111〉 silk texture appears in the copper layer and the aluminum core.

     

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