Anomalous quasiplasticity, spallation, and thermal damage in fused silica under laser-induced quadruple stress waves and multi-field coupling effects

Spallation and thermal damage limit the application of fused silica under extremely intense lasers. Herein, the unclear underlying mechanisms, including extreme-irradiation-induced plasticity-related behaviors were studied based on first-constructed cross-scale models, molecular dynamics simulation, and multimodal characterization. Material spallation originated from the anomalous “quasiplasticity” and phased propagation of micro-cracks under quadruplex elastoplastic waves. Although the fastest primary wave could not cause macroscopic deformation, it could lead to micro-plasticity phenomena (ring-structure transformation and point-defect proliferation) due to material phase transformation and destabilizing effects. Subsequently, conjugate secondary and head elastoplastic waves governed initialization processes of micro-cracks, where primary-wave-induced E’-Center and NBOHC defects played roles of “damage precursors”. Concomitantly, transitional deformation zones containing massive strip-like-distributed cavities (similar to “immature” micro-cracks) were generated around micro-cracks. There was a cascading evolution process of point defects, cavities, and micro-cracks under phased energy input from waves, causing an anomalous “quasiplasticity” process within brittle fused silica. It differs from transient fracture processes of brittle materials. Finally, the Rayleigh waves trapped on surfaces attracted micro-cracks towards them, causing disastrous surface damage. The thermal damage originated from the volcanic vents formed within 3∼4 ns, which was induced under the comprehensive action of the impact of elastoplastic waves, cascading solid-liquid-gas phase transition, GPa-level pressure difference between ablated zones and air, and fluidic flow disturbances. The whole time-evolution sequence axis diagram of the material failure process was drawn based on these. Summarily, this work could offer novel insights into the anomalous “quasiplasticity”, spallation, and thermal damage phenomena of fused silica under intense lasers.