Structure inhibited pit initiation in a Ni-Nb metallic glass

A model metallic glass Ni50Nb50, which would undergo a polymorphous transformation during devitrification, was selected to clarify the correlation of amorphous structure with corrosion. The electrochemical polarization behaviour, film breakdown and composition of surface film have been studied in detail by comparing the amorphous alloy with its crystalline counterparts. Interestingly, it was found that the pit initiation is inhibited greatly on amorphous sample relative to the crystallized one. The origin is thought to be related to the defective interface beneath passive film that inhibits the formation of pitting precursors in corrosion. (C) 2009 Elsevier Ltd. All rights reserved.