To understand the underlying microstructure evolution and joining mechanism of ultrasonic spot welded Cu/Cu joint, the microstructure and crystallography analysis were investigated. The grain size, grain boundary, misorientation angle, Kernel Average Misorientation, Schmid factor and crystal orientation along the weld thickness were heterogeneous and unsymmetrical. The changes of corresponding microstructural and crystallographic features were more obvious for the top sheet comparing with the bottom sheet. The {111} <110> texture, nano-sized equiaxed induced by discontinuous dynamic recrystallization and refined elongated grains because of continuous dynamic recrystallization were formed at the welding interface. The nucleated fine grains between the elongated grains attributing to continuous dynamic recrystallization were beneficial to the grain boundary migration and consequent the achievement of the interfacial metallurgical bonding.

为了了解超声点焊铜/铜接头的基本微观结构演变和连接机制，对微观结构和晶体学分析进行了研究。沿着焊缝厚度的晶粒尺寸、晶界、取向差角、核平均取向差、施密德因子和晶体取向是不均匀和不对称的。与底层相比，顶层相应的微观结构和晶体学特征的变化更为明显。焊接界面形成{111}<110>织构、不连续动态再结晶诱导的纳米级等轴晶和连续动态再结晶细化的拉长晶粒。