Diffusion studies in amorphous NiZr alloys and their relevance for solid state amorphizing reactions

Tracer impurity and self-diffusion measurements have been made on vapor-deposited amorphous NiZr (a-NiZr) alloys using radioactive tracer, secondary ion mass spectrometry and Rutherford backscattering techniques. The temperature dependence of tracer diffusion in a-NiZr can be represented in the form D = D₀ exp( -Q kT), with no structural relaxation effects being observed. Atomic mobilities in a-NiZr were observed to increase dramatically with decreasing atomic radius of the diffusing atom and also with decreasing nickel content for nickel concentrations below about 40 at.%. These diffusion characteristics in a-NiZr are remarkably like those in α-Zr and α-Ti, suggesting similarities in the diffusion mechanisms. The relevance of these diffusion data for the solid state amorphizing reaction is discussed.