Atomistic simulation of the preheating treatment and crystal orientation influences in the hardness of cold gas dynamic sprayed nickel coating unto the copper substrate

As a modern surface modification technique, cold gas dynamic spray (CGDS) is commonly used to improve the quality of the surface. Molecular dynamics (MD) simulations were used to systematically analyse the effects of preheating treatment and crystal orientation of copper (Cu) substrate on coating surface generation mechanisms by nickel (Ni) particles in the cold gas dynamic spray. In this study, the embedded-atom method (EAM/alloy) potential was adopted to describe the interaction of Ni atoms in the particle and Cu atoms in the substrate. The amorphization tendency and temperature distribution in our simulation are consistent with the experimental results from the literature. Simulation results show that the particle/substrate impact in the interfacial region undergoes a structural transformation from the face-centred cubic structure into different local atomic structure upon the impact of the Ni particle. After the impact, recrystallization of the crystal lattice occurs and due to unrecoverable plastic deformation, the substrate surface is residually dimpled. Comparing the hardness of three different crystal orientation of Cu surface, it is obvious that [1 1 0] is the hardest surface and the [1 0 0] the weakest. With regard to the effect of preheating temperatures, simulation results show that Cu substrate softens, and Cu adhesiveness increases when preheating temperature is higher.