Radiation-enhanced diffusion in amorphous Ni-Zr alloys

Radiation-enhanced diffusion of Cu and Au tracer impurity atoms during ${\mathrm{Kr}}^{+}$ irradiation has been measured in amorphous ${\mathrm{Ni}}_{50}$ ${\mathrm{Zr}}_{50}$ and ${\mathrm{Ni}}_{35}$ ${\mathrm{Zr}}_{65}$ alloys in the range 80-573 K. At low temperatures, the spreading of the thin impurity layers was due to ion beam mixing and was independent of temperature. Above ≅400 K, the diffusion coefficient of Cu in ${\mathrm{Ni}}_{50}$ ${\mathrm{Zr}}_{50}$ shows Arrhenius behavior with an apparent activation enthalpy of ≅0.55 eV, and it depends on the square root of dose rate. The radiation-enhanced diffusion coefficient is greater for Cu than Au and is also larger in the Zr-rich alloy.