Microstructural evolution and mechanical properties of CrCoFeMnNi high-entropy alloys under femtosecond laser ablation: A molecular dynamics approach

High-entropy alloys (HEA) represent a significant advancement in the field of alloy theory, distinguished by their exceptional properties, including high hardness, strength, plasticity, and remarkable thermal stability. This study utilizes molecular dynamics simulations to investigate the femtosecond laser ablation process of the CrCoFeMnNi high-entropy alloy, with a focus on the variations in internal microstructure, temperature, stress, and mechanical properties. The results indicate that an increase in laser energy density leads to a substantial elevation in both temperature and stress within the lattice structure. At a fixed pulse width, higher laser energy densities correlate with elevated lattice temperatures and accelerated cooling rates, highlighting the pronounced influence of laser energy on thermal dynamics. Conversely, the effect of pulse width on the temperature relaxation time is comparatively minimal. When the temperature at the laser focal point exceeds 5000 K, the morphology of the high-temperature region aligns with the laser beam, demonstrating that femtosecond lasers exhibit minimal thermal diffusion effects. Furthermore, residual stress at the laser focus can reach up to 30 GPa, primarily resulting from thermal expansion and lattice compression during phase transformations. The study also examines the evolution of dislocation structures, with 1/6<112> dislocations identified as the predominant type. Overall, this work provides critical theoretical insights and technical guidance for the application of high-entropy alloys in laser ablation processes, paving the way for future research and industrial applications.