Evidence of Highly Collective Co Diffusion in the Whole Stability Range of Co-Zr Glasses

Using a radiotracer technique, we have measured the isotope effect E0ex0ex=0ex0exdln(D)/dln(m1/2) of Co diffusion in CoₓZr_1-x glasses for 0.31≤x≤0.86. E is close to zero (E0ex0ex=0ex0ex0±0.1) in the whole range, covering 3 orders of magnitude in the diffusivity, despite the existence of large activation volumes. These results strongly suggest a highly collective diffusion mechanism to be a quite general phenomenon in metallic glasses and point to diffusion via delocalized thermal effects at certain compositions.