Surface hardness and scratch characteristics of nanosecond laser colored Ti-based metallic glass

Abstract

Pulsed laser irradiation is widely used for coloring metallic glass (MG) surfaces due to its efficient and clean processing characteristics. However, the hardness and tribological properties of laser colored MG surfaces have rarely been studied. In this study, various colors were prepared on Ti-based MGs by nanosecond pulsed laser irradiation, and the mechanical properties of the colored surfaces were subsequently investigated. Before hardness testing, the colored surfaces were slightly polished and characterized for surface morphology and phase composition. The hardness of the colored surfaces was measured by a nanoindentation instrument, and the corresponding load depth curves and residual indentations were obtained. The results showed a 39% increase in hardness compared to the as-cast surface. Scratch tests were performed to investigate the tribological properties of the colored surfaces. The residual scratches and three dimensional (3D) topographies exhibited diverse features, and the scratch damage mechanism was analyzed accordingly. This study broadened the knowledge of surface hardness and tribological properties, and illustrated the application potentials of laser colored MGs.