Diffusion-limited and asymmetric growth of amorphous layer in Ni/Zr bilayer upon annealing

Asymmetric growth of amorphous layer in a Ni/Zr bilayer, in which a thin disordered interlayer is preset, upon annealing at medium temperatures is observed by molecular-dynamics simulation with an n-body potential. It is shown that the amorphous layer is extended from the interlayer with different speeds toward two opposite directions and that the growth kinetics follows time dependence of t1/2, indicating amorphization upon annealing in the Ni/Zr bilayer is indeed through a diffusion-limited reaction. Besides, two low temperature limits allowing the growth of amorphous layer toward Ni and Zr layers are also obtained.