冷喷涂Ni涂层的微观组织

Microstructures of cold-sprayed Ni coating

采用SEM和TEM对冷喷涂Ni涂层的微观组织进行表征。结果表明:在粒子尺寸范围内,Ni涂层的微观组织有明显差异:粒子界面处,微观组织以带状晶和等轴晶为主;界面附近以位错墙、位错缠结形貌为主,且距离界面越近,晶粒细化越明显;两区域对应的组织演变机制分别是高应变速率动态再结晶机制和位错运动导致的晶粒细化机制。

The microstructures of cold-sprayed Ni coating were characterized by SEM and TEM. The results show that the local microstructure in a particle of the cold-sprayed Ni coating reveals a quite inhomogeneous appearance. Elongated grains and equiaxed grains are typical microstructures at the particle-particle interface, while the regions near the interface exhibit heavily deformed appearance with a large number of dislocation walls or dislocation tangles. Moreover, the grain refinement near the interface is more pronounced than that on the periphery of the interface. The main mechanisms for microstructural evolution at, and near the interface are the dynamic recrystallization under high-strain-rate deformation and the plastic strain-induced grain refinement due to dislocation movement, respectively.