Microstructure characterization and nanomechanics of cold-sprayed pure Al and Al-Al2O3 composite coatings

The present study investigated the microstructure and nanomechanical properties on the cross and normal planes of cold sprayed pure Al and Al-based composite coatings. The inhomogeneous plastic deformation of Al particles took place with the occurrence of grain refinement along the particle boundaries. No preferred orientation distribution in the cold sprayed Al coating was observed because of the random impact direction of particles on the surface of substrate or the previously formed coating. The hammering effect of hard Al2O3 particles enhanced the plastic deformation of Al particles. Anisotropic mechanical properties were revealed, i.e., higher hardness and elastic modulus were obtained on the cross plane. Compared with pure Al bulk metals, both the cold sprayed pure Al and Al-based composite coatings demonstrated the improved tribological properties in terms of lower wear volume and reduced friction coefficient.