Acid corrosion process of Fe-based bulk metallic glass

For the bulk metallic glass (Fe44.3Cr5Co5Mo12.8Mn11.2 C15.8B5.9)(98.5)Y-1.5 it is demonstrated that C plays a very important role in the acid corrosion process. Immersion in either 0.5 M H2SO4 or 1 M HCl yields constant-rate corrosion with the formation of a loose permeable C-rich layer. The underlying region of the corroding glass exhibits characteristic morphological features on the micro- and nanometre scale. The nanoscale features are explained by selective dissolution where C is the major slow component. The microscale features are attributed to a pitting-like process. It is demonstrated that ill situ AFM is a powerful tool to visualize the incipient "micro-pit" evolution. (C) 2012 Elsevier Ltd. All rights reserved.