Atomistic simulation on the deposition behavior of cold spray

Abstract

Cold spray is an effective method for surface coating, which has been applied in various engineering areas. However, it is difficult to directly observe the dynamic deformation process in experiments. This paper applies the molecular dynamics simulation to model the deposition of a monocrystalline Cu particle onto a Cu substrate and, subsequently, carries out a systematic study on the deposition mechanism and microstructure evolution. The results indicate that the deposition process consists of an impact stage and a relaxation stage. It is mainly the high speed collision and the friction following the collision that lead to particle deposition, which, under different circumstances, can be defined as surface deposition or penetration deposition. Two methods, namely, drastic shear deformation and cooling in the relaxation stage, can help form nanocrystallines. Jetting and melting are not the necessary factors for the deposition of nano-sized particles. The formation of dislocation lines is influenced by impact velocities. At lower impact velocities, the dislocation lines are mainly distributed near the contact surface. However, when the impact velocity is higher, dislocation lines are almost uniformly distributed in the particle.