Evaluation of the effects of the crystallinity of kinetically sprayed Ni-Ti-Zr-Si-Sn bulk metallic glass on the scratch response

A bulk amorphous Ni-Ti-Zr-Si-Sn powder produced using an inert gas atomization was sprayed by a kinetic spraying process that is basically a solid-state deposition process onto a mild steel substrate and they were successfully overlaid onto the mild steel substrate. In order to evaluate the tribological behavior of the sprayed Ni-Ti-Zr-Si-Sn bulk metallic glass coatings, a partially crystallized coating and a fully crystallized coating were prepared by isothermal heat treatments. Tribological properties were investigated-friction coefficient, hardness and amorphous phase fraction of coating layer. Surface morphologies and depth in the wear tracks were observed and measured by scanning electron microscopy and α-step. From the examination of the scratch wear track microstructure, transition from ductile-like deformation micro-cutting to brittle-deformation micro-fracturing in the scratch groove was observed with the increase of the crystallinity