Orientation-induced differences in ablation and defect evolution of Ni single crystals irradiated by femtosecond laser

Femtosecond laser micromachining is critical for precision manufacturing of single-crystal Ni components, such as turbine blades with complex cooling-hole, where curved surfaces expose diverse orientations that may alter ablation and defect evolution. Using a coupled two-temperature model-molecular dynamics framework, the orientation effects of (100), (110) and (111) on ablation and defect evolution under laser irradiation were investigated. Ablation behaviour (melting depth, ablation depth and ejecta) shows negligible orientation dependence over studied fluence range. In contrast, laser-induced stacking faults (LISF) are strongly orientation dependent: absent on (100), intermediate on (110), and maximal on (111), with the trend persisting across broader orientation space. Stress analysis reveals that von Mises stress distinguishes the propensity for Shockley partial dislocation nucleation, while the resolved shear stress at the LISF front correlates positively with the dislocations’ slip velocity. These findings enable defect-informed process optimisation and motivate future studies on long-term degradation of laser-processed superalloy components.