Simultaneous improvement in surface quality and hardness of laser shock peened Zr-based metallic glass by laser polishing

Abstract

Laser shock peening (LSP) is an effective method to improve the plasticity of metallic glasses (MGs) but it also deteriorates the surface quality and decreases the surface hardness, which in turn hinders the applications of MGs. Accordingly, this study was attempted to achieve the simultaneous improvement in surface quality and hardness of LSPed Zr-based MG by nanosecond pulsed laser polishing. LSP of the MG was firstly performed by using a high-energy pulsed laser to prepare the LSPed MG samples, and then laser polishing of the LSPed MG surface was conducted by using nanosecond pulsed laser. The effects of laser polishing parameters (i.e., average laser power, scanning speed, overlap rate, and number of irradiation cycle) on the surface quality and hardness of the LSPed MG were investigated in detail. The experimental results showed that after laser polishing under specific conditions, a 90% reduction in surface roughness and a 11 % increase in surface hardness could be achieved for the LSPed MG surface. This study provides a simple and effective method to simultaneously improve the surface quality and hardness of LSPed MGs, which would be of great significance for the practical engineering applications of MGs.