Hydrogen-induced crystallization of an amorphous metal

The influence of hydrogen on the structural stability of an amorphous nickel has been analyzed by molecular dynamics simulation. We find that the volume of the amorphous metal increases nonlinearly with the hydrogen concentration and that it crystallizes at a certain critical concentration. The crystallization is shown to be caused by hydrogen-induced transition from the amorphous to the supercooled liquid state, and the change of diffusion mechanism from atomic hopping to string-like collective motion is also observed at the transition.