Molecular dynamics simulations of warm laser shock peening for monocrystalline nickel

Compared to traditional laser shock peening, warm laser shock peening (WLSP) exhibits superior residual stress and thermal stability. Herein, the micro-mechanism of single-crystal nickel by WLSP is investigated via molecular dynamics (MD) simulations. The results reveal that certain slip systems, i.e., (1¯1¯1) [1¯1¯0], (11¯1¯) [110] and (111) [01¯1¯], are sequentially activated during WLPS. Then, these slip systems intersect and cross-slip of dislocations occurs, forming dislocation tangles and dislocation walls. These dislocation walls further form sub-grain boundaries when the shock pressure reaches 90 GPa, transforming single-crystalline Ni into polycrystalline Ni. In addition, WLSP at 450 K is beneficial for the formation of Hirth sessile dislocations and improves the properties of monocrystalline Ni.