The Soret effect in bulk metallic glasses

Compositional inhomogeneity induced by the Soret effect was studied in two Zr-based bulk metallic glasses (BMGs): Zr₅₀Cu₅₀ and Zr₅₀Cu₄₀Al₁₀ (at%), and one Cu-based BMG: Cu₆₀Zr₃₀Ti₁₀ (at%), all of which were prepared by rapid solidification. The concentration of Cu increases from the surface to the interior, while the concentrations of Zr, Ti and Al decrease. The magnitude of the Soret effect is found to be highly dependent on the sample size and interactions between the diffusing atoms in bulk metallic glasses. For the Zr₅₀Cu₅₀ alloy, a large sample size favors the Soret effect, because of the longer diffusion time it affords compared to a small sample. Further, the additions of Al and Ti in the Zr-Cu BMGs reduce the magnitude of the Soret effect by the formation of short-range order and/or inter-atomic clusters. © 2006 Elsevier Ltd. All rights reserved.