Femtosecond Laser Eliminates Grain Boundary Defects in Copper Film: A Molecular Dynamics Study

The crystallographic and mechanical properties' change of bicrystal copper film under different femtosecond laser intensities is studied. Meanwhile, a simulation that combines the tow-temperature model and molecular dynamics method is conducted. It is showed that within a certain range of laser intensity, polycrystalline copper film can be transferred into a single crystal, which is in accordance with some femtosecond laser ablation experiments. Moreover, the mechanical properties' changes brought by laser ablation are studied by uniaxial tensile and compression test. Laser-induced single crystal shows a noticeable enhancement in tensile strength while the compression strength is similar to that of the bycrystals. However, due to the scattered points defects formed during the crystallization, its mechanical properties still underperform the ideal single crystal.