ECAP结合退火工艺制备铜铝双金属复合棒材的界面组织及结合性能

Interfacial Microstructure and Bonding Property of Cu/Al Bimetallic Composite Rod Fabricated by Equal Channel Angular Pressing (ECAP) and Post-annealing

摘要:

利用室温4道次ECAP挤压结合退火工艺成功制备铜铝双金属复合棒材。采用扫描电镜（SEM）、能谱分析（EDS）、X射线衍射分析（XRD）和电子背散射衍射（EBSD）等方法研究铜铝双金属复合棒材结合界面微观组织，并通过剪切试验测试其界面结合强度。结果表明，在ECAP剧烈剪切作用下，铜铝双金属复合棒材首先通过塑性变形在界面处产生机械结合，后续退火热处理促进了铜铝原子之间相互扩散，在压力、温度和浓度梯度综合作用下，Cu/Al界面处形成了良好的冶金结合，界面层厚度约为1.47 μm，生成的金属间化合物主要为CuAl2；界面层内晶粒细小、均匀，为大角度晶界结构的超细晶组织，无明显的择优取向。铜铝双金属复合棒材平均剪切强度为28.94 MPa，界面结合质量良好，剪切破坏形式主要为脆性断裂。

Abstract:

Cu/Al bimetallic composite rod was successfully fabricated by 4 passes ECAP at room temperature and post-annealing. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) were used to investigate the microstructure of the bonding interface of Cu/Al bimetallic composite rod, and the interfacial bonding strength was also tested by shear test. The results show that under the severe shear deformation during ECAP process, mechanical bonding occurred firstly at the interface of the Cu/Al bimetallic composite rod through plastic deformation, and then the mutual diffusion between copper and aluminum atoms were promoted during the post-annealing. Under the combined effects of large pressure, high temperature and concentration gradient, a good metallurgical bonding at the interface of the Cu/Al bimetallic composite rod was formed. The thickness of Cu/Al interface layer was about 1.47 μm and a new phase of intermetallic compound CuAl2 was generated, consisting of ultrafine grained (UFG) microstructures with high angle grain boundaries and homogeneous distribution, and there was no obvious preferred grain orientation. The average shear strength of Cu/Al bimetallic composite rod was 28.94 MPa, showing the good interface bonding quality. Moreover, the main shear failure mode was brittle fracture.