Radiation-enhanced diffusion in amorphous Pd-Cu-Si

Abstract

Diffusion during ${\mathrm{He}}^{+}$, ${\mathrm{Ne}}^{+}$, and ${\mathrm{Xe}}^{+}$ irradiations of trace amounts of Au in melt-spun amorphous ${\mathrm{Pd}}_{78}$${\mathrm{Cu}}_{6}$${\mathrm{Si}}_{16}$ has been experimentally investigated. Diffusion constants were measured by following the changes in ion-implanted Au profiles with Rutherford-backscattering spectrometry. Heat treatments and simultaneous irradiations were performed as a function of temperature (533--588 K), ion flux, and ion mass. Total integrated fluences being very small, ion-beam-mixing effects are negligible. More than an order of magnitude enhancement in the diffusion was observed because of irradiations. This enhancement saturates at higher fluxes, the level being independent of ion mass, i.e., independent of collision-cascade parameters. Except at higher temperatures, where the enhancement decreases, the temperature dependence of the diffusion-saturation level is similar to that of the diffusion without irradiation. The data suggest that vacancylike defects play a significant role in the diffusion.