Effect of surface finishing of a Zr-based bulk metallic glass on its corrosion behaviour

摘要

Zr-based metallic glasses passivate spontaneously, but exhibit also a certain pitting susceptibility. On the example of the Zr_(59)Ti_3Cu_(20)Al_(10)Ni_8 alloy studied in 0.01 M Na_2SO_4 + x M NaCl (x = 0-0.1) electrolytes it is demonstrated that the surface finishing state and the pre-exposure conditions can significantly influence the free corrosion and anodic polarisation behaviour. Mechanical fine-polishing procedures can lead to extremely smooth topographies but also to Cu enrichment at the surface. This yields a pronounced Cu dissolution at low anodic polarisation prior to stable passivity and increases the pitting initiation susceptibility as compared to mechanically ground surface states.