In-situ Study on the Microstructural Evolution and Strengthening Mechanism of Fe35Co30Ni30Ta2Mo2Cu1 Alloy under Laser Shock Peening

This study investigates the effects of laser shock peening (LSP) on the microstructure and mechanical properties of Fe35Co30Ni30Ta2Mo2Cu1 high-entropy alloy (HEA). Compared to the as-cast condition, LSP treatment increases the yield strength and ultimate tensile strength by approximately 320 MPa and 210 MPa, respectively, while maintaining comparable elongation. Microstructural characterization reveals that LSP induces grain refinement, increased dislocation density, and the formation of nanoscale Cu-rich precipitates. These features promote dislocation multiplication and improve slip compatibility, reducing strain localization and stress concentration. Furthermore, during deformation, the development of high-angle boundaries (>15°) due to grain subdivision facilitates stress relaxation and sustains ductility. The results elucidate the role of LSP in tailoring hierarchical microstructures to enhance the strength–ductility synergy of HEAs, providing insights for designing high-performance alloys.