Molecular dynamics study on the diffusion process of AuAgCuNiPd high-entropy alloy metallurgy induced by pulsed laser heating.

As novel alloy materials with outstanding mechanical properties, high-entropy alloys have a wide range of promising applications. By establishing individual Au, Ag, Cu, Ni, and Pd nanolaminates with face-centered-cubic lattice structure arrangements, molecular dynamics simulation is carried out to track the diffusion process of AuAgCuNiPd high-entropy alloy metallurgy, which is induced by pulsed laser heating. The temperature, potential energy, and kinetic energy are analyzed to evaluate the metallurgy. The snapshots and atomic fractions are presented to show the mass transfer between metallic nanolaminates. The diffusion process is firstly observed 0.3 ns after the central point for pulsed laser heating (absorbed laser energy density at 7 kJ cm-3 and pulse duration of 0.5 ns). Meanwhile, the degrees of atomic activity for Au, Ag, Cu, Ni, and Pd are assessed by calculating the mean square displacement and diffusion coefficient. Ni has a slightly larger diffusion coefficient than the other four metallic elements. Moreover, after the central point of laser irradiation, the kinetic energy of the system reduces, while the potential energy increases, which relates to the transition from nanolaminates to high-entropy alloys. A critical absorbed laser energy density of 6 kJ cm-3 with a relative error of 8.3% for the generation of AuAgCuNiPd high-entropy alloys is found. The order of constituent nanolaminates configured with the earlier initiation of diffusion between atoms in the neighboring nanolaminates speeds up the metallurgy.