Interface behavior of particles upon impacting during cold spraying of Cu/Ni/Al mixture

Cold spraying (CS) deposition depends to a large extent on the particle interface behavior during high velocity impacting, which may involve extensive plastic deformation, recrystallization, and localized melting and resolidification. In this study, commercially pure Cu, Ni and Al powders were used as feedstock to produce Cu/Ni/Al composite coatings with CS. The focused ion beam (FIB) technique was used to characterize the particle interface. In addition, an Eulerian model was developed to study the impacting. Results show that Cu, Ni and Al particles have different impact behaviors during deposition. Although the ratio of Cu, Ni and Al is 1:1:1 in the feedstock, their fractions in the composite coating are about 35 vol.%, 17 vol.% and 48 vol.%, respectively. Because of severe deformation, recrystallization, twins and dense dislocations appear in the impacted Cu particles. The detachment of a thin Al layer from the bulk of Al particle at the surrounding contact zone reflects the residual tensile stresses developed near the interface.