Elastic Isotropy of Cold Sprayed Coatings

Resonant ultrasound spectroscopy (RUS) was applied to analyze the elastic anisotropy of thick Cu, Al, Ti, and Ni coatings prepared by cold-spraying, and to determine the respective elastic moduli. The results show that for all studied materials the coatings exhibit only negligible deviations from perfect isotropy. Moreover, especially for the Cu and Al coatings the obtained elastic constants (Young's modulus, shear modulus and bulk modulus) are comparable with those of the same material in polycrystalline bulk. Significant differences in the internal friction parameters of the individual coatings were recorded and were shown to be correlated with the respective elastic stiffnesses. Based on the results, strain accommodation mechanism of cold spray deposits is further suggested in the paper.