Microstructure and surface chemistry of amorphous alloys important to their friction and wear behavior

Abstract

An investigation was conducted to examine the microstructure and surface chemistry of amorphous alloys, and their effects on tribological behavior. The results indicate that the surface oxide layers present on amorphous alloys are effective in providing low friction and a protective film against wear in air. Clustering and crystallization in amorphous alloys can be enhanced as a result of plastic flow during the sliding process at a low sliding velocity and at room temperature. Clusters or crystallites with sizes up to 150 nm and a diffused honeycomb-shaped structure are produced on the wear surface. Temperature effects lead to drastic changes in surface chemistry and friction behavior of the alloys at temperatures up to 750°C. Contaminants can come from the bulk of the alloys to the surface on heating and impart to the surface oxides at 350°C and boron nitride above 500°C, The oxides increase friction while the boron nitride reduces friction drastically in vacuum.