Radiation-enhanced diffusion in a metallic glass was studied under  in situ  high-energy electron irradiation in a transmission electron microscope (figure 12). Irradiation was performed on thin-foil cross-sectional specimens which had been obtained from Ni-Zr bulk diffusion couples. The diffusivity under electron irradiation was deduced from the growth rate of a thin Ni-Zr amorphous film at the Ni/Zr interface. The results showed that Ni was the most mobile species under these conditions, and that radiation damage occurred in glassy metals at a lower electron energy; relative to the corresponding crystalline compound. The dose-rate sensitivity of the radiation-enhanced diffusion appeared to depend upon the energy of the electron beam. The process of radiation displacement in metallic glasses was modelled within the framework of the free-volume theory for the structure of metallic glasses. This simple model could qualitatively explain the present results.

S.Bellini, A.Montone, M.Vittori-Antisari: Physical Review B, 1994, 50[14], 9803-9