Local Structural and Tracer Diffusion Mechanism in Amorphous Fe-based Alloys

Local structure and tracer diffusion mechanism in amorphous Fe and Fe80B20 solids is studied using the statistic relaxation (SR) model containing 2×105 atoms. It was found a large number of bubbles which could break-up and leads to diffusion. A bubble diffusion mechanism is proposed and the diffusion coefficient determined in term of this mechanism is in reasonable agreement with experimental data. The decrease in diffusion coefficient upon thermal annealing observed experimentally for most amorphous Fe-based alloys is interpreted as a result of reduced number of bubbles in system.