Effect of laser shock peening and its size-dependence on the compressive plasticity of Zr-based bulk metallic glass

In this study, laser shock peening (LSP) has been performed on brick-shaped Zr-41.2-Ti13.8Cu12.5Ni10Be22.5 (vit1) bulk metallic glass (BMG) with different dimensions but the same aspect ratio of 2:1 to study the effects of LSP treatment and size-dependence on plasticity and compressive strength at room temperature. The results show that: (1) the plasticity of LSP treated specimens is still size-dependent, the smaller the specimen size is, the higher plasticity and compressive strength it has, which means the size effects of BMG can be preserved and inherited during LSP. (2) The same LSP treatment has different effects on different size specimens, the smaller the specimen size is, the greater effect it has, which indicates that LSP process causes much more obvious size dependence in BMG. The mechanism for plasticity improvement can be attributed to the increase of free volume and the generation of deep compressive residual stress induced by LSP for each size specimen. Therefore, smaller specimen is corresponding with larger volume fraction of LSP affected zones and greater LSP effect.