Molecular dynamics simulations of microstructure and dislocation evolution of single-crystal Ni-based superalloys under femtosecond laser loading

In this paper, molecular dynamics simulations are employed to investigate the temperature, stress distribution, microstructure and evolution of dislocations in single-crystal Ni-based superalloys during femtosecond laser drilling of micro-holes. The results indicate that the temperature and stress variations in the model system increase with the increment of laser energy density. The pulse width has a relatively low effect on temperature and stress variations. At the same time, an increase in dislocations is primarily related to energy density and stress distribution. The number of dislocations increases with the energy density, with the 1/6<112> dislocation showing the highest increase ratio. The densest concentration of dislocations occurs at the hole walls. Dislocations and stacking faults gradually penetrate the precipitate phase under the influence of temperature and reach a stable state as the relaxation time increases. The above research findings provide important theoretical guidance for understanding the microstructure evolution and changes in the mechanical properties of single-crystal Ni-based superalloys during femtosecond laser processing of micro-holes.