Tracer diffusion in amorphous Ni-Zr alloys

This paper describes tracer impurity diffusion coefficients for Co and Hf were measured in a series of amorphous NixZr(1-x) alloys in the range 0.30 < x < 0.70 and at temperatures between 250 degrees C and 350 degrees C. The diffusion coefficients for the Co atoms are between 2 and 4 orders of magnitude greater than those for Hf depending on alloy composition and temperature. Diffusion coefficients for Hf are independent of alloy composition, whereas those for Co decrease strongly with increasing Ni content. The activation enthalpies of diffusion and the pre-exponential factors were both found to be significantly smaller for the Hf than the Co tracer impurity atoms. These results are discussed in terms of possible diffusion mechanisms in amorphous metallic alloys