Influence of ultrafast laser processing on amorphous structures - based on molecular dynamics simulation

Ultrafast laser processing technology exhibits exceptional precision and irreplaceable functionality in the fabrication of micron and nanometer-scale devices. However, its short action time presents challenges for observing and studying the interactions between ultrafast lasers and materials. This study employs molecular dynamics simulations to specifically investigate the application of ultrafast laser processing in treating amorphous structural defects on Ni-Fe alloy surfaces. The simulations reveal the impact of energy deposition on the material's crystallization behavior on a nanosecond timescale. It was found that the crystallization temperature increases with the rising rate of temperature change, although the final crystal structure remains unchanged. Enhanced energy deposition accelerates lattice formation, improves atomic ordering, and reduces the crystallization time from 4.5 ns to 3.2 ns. The lattice phase transition is completed within 0.5 ns, and an increased incubation temperature effectively minimizes the proportion of the amorphous phase. The simulation results clearly illustrate the fundamental nucleation and growth mechanisms, providing valuable insights into the effects of ultrafast laser processing on surface lattice structures and atomic dynamics. Moreover, these findings establish a theoretical foundation and offer data support for developing future material processing methods.