焊接能量对铜铝超声波焊接接头界面元素互扩散的影响

Effect of Welding Energy on Interdiffusion Behavior of Interfacial Elements in Cu/Al Joints Welded by Ultrasonic Welding

采用超声波焊接方法对0.3 mm厚的Cu、Al箔片进行焊接,通过扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等方法对接头界面组织和成分进行了研究,对界面金属间化合物(IMCs)的生成演变进行了探讨,并对焊接接头进行了剪切力测试。结果表明:当焊接能量较小时,Cu、Al元素在界面处发生互扩散,逐步形成了扩散反应区,析出α-Cu和α-Al固溶体相,随着焊接能量的增大,Cu/Al界面处发生变形,形成高密度位错累积,同时高温停留时间增长,Cu、Al元素快速扩散,形成第二相的驱动力增加,逐渐析出CuAl2和Cu9Al4相。随着焊接能量继续增大,反应区慢慢生长,反应层也逐渐变厚,适中的反应层厚度能提高接头强度。

0.3 mm thick Cu, Al foils were welded by ultrasonic welding. The interface structure and composition of the welded joint were studied by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD), and the formation and evolution mechanism of interface intermetallic compounds(IMCs) were discussed,and the shearing force of the welded joints was tested. The results show that, when the welding energy is small, Cu and Al elements diffuse at the interface, the diffusion reaction zone is gradually formed, and the α-Cu and α-Al solid solution phases are precipitated. With the increase of the welding energy, the deformation at the Cu/Al interface occurs, resulting in high-density dislocation accumulation, the high temperature residence time increases, the Cu and Al elements diffuse quickly,the driving force for formation of secondary phases increases and CuAl2, Cu9Al4 phases are precipitated gradually. As the welding energy continues to increase, the reaction area grows slowly and the reaction layer is gradually thickened. Proper reaction layer thickness can improve the strength of the welded joint.