Oxidation of Cu60Zr30Ti10 metallic glasses

Cu–Zr-based bulk metallic glasses are of increasing interest due to their excellent properties. Cu-rich Cu60Zr30Ti10 and Zr-rich Zr69.5Cu12Ni11Al7.5 glasses (numbers indicate at.%) are examples which combine good glass forming ability with excellent mechanical properties making them a material of choice for a variety of applications. Any application, however, requires adequate thermal stability, i.e. resistance against crystallization and oxidation. The aim of this paper is a detailed investigation on the oxidation of Cu60Zr30Ti10 metallic glasses. Whereas oxidation in Zr-rich Zr69.5Cu12Ni11Al7.5 is assumed to be controlled by oxygen diffusion through a homogeneous scale towards the ZrO2/glass interface, in Cu-rich Cu60Zr30Ti10 metallic glasses multilayered scales were found to develop with an assembly of Cu-oxide needles at the outer surface. Due to developing stresses and the formation of voids the outer oxide layer loses contact at the interface and starts to peel off during ongoing oxidation.