Cross-scale mapping relationship of micro-deformation to macro-plasticity in metallic glasses regulated by laser shock peening

In this work, laser shock peening (LSP) was used to conduct a controlled surface pretreatment on a Zr-based metallic glass (MG), and then nanoindentation creep test was considered as a high spatial resolution probe to systematically explore the influence of LSP on the time-dependent deformation behavior of the MG. The results revealed that LSP greatly enhanced the creep resistance of the MG - the minimum suppression rate was as high as 64%. Microscopic mechanism analysis confirmed that LSP simultaneously decreased the characteristic volume of the shear transformation zones (STZs) and the thermal activation volume (ΔV∗) by 59 –61%, leading to a creep mechanism transition. Macroscopic mechanical evaluations further revealed that the bending plasticity of MG had been improved after the LSP treatment, and the fracture mode of the MG had changed from a typical cleavage brittle fracture mode to a shear-dominated mode. From a combined analysis of the multiple-scale experimental results, LSP was discovered to re-configure the distribution and dynamic flow path of microscopic plastic flow in MGs by building a functional surface resistive layer, refining the STZ scale, and suppressing their long-range cooperative evolution, thus propelling the deformation to evolve from sudden shear band burst to multi-nucleated, separated and steady progressive shear flow, ultimately obtaining synergistic enhancement of macroscopic plasticity. This study not only reveals the cross-scale mapping relationship between the micro-deformation and macro-plasticity of MGs under LSP, but also offers a reliable experimental and theoretical reference for devising new toughening strategies for MGs.