EFFECT OF MULTIPLE DEFORMATIONS ON THE AMORPHIZATION OF NI-ZR DIFFUSION COUPLES

The solid state amorphization of a Ni-Zr diffusion couple subjected to impulsive plastic deformation has been studied in the presence, at th e Ni-Zr interface, of an amorphous layer a few nm thick. Previous expe riments have shown that the effective interdiffusion coefficient in th e metallic glass is strongly enhanced by the deformation process with a resulting fast growth of the amorphous phase during codeformation of elemental couples. If a relaxed glassy film is already present at the interface, the main effect of the deformation is a reduction of the f ilm thickness. Careful observation of the amorphous phase-crystalline Zr interface reveals local thickness variations suggesting that both d eformation and fast diffusion occur inhomogeneously in thin shear band s, as expected for a relaxed metallic glass deformed at the strain rat es of the present experiment.