Influence of Cu addition on corrosion behavior and tensile performance of Ni-30Co-16Cr-15Mo-6Fe alloy

Abstract

Corrosion behavior in 5.2 M aqueous hydrofluoric acid solution and tensile properties of Ni-30Co-16Cr-15Mo-6Fe-xCu (x = 0, 0.5, 2, and 6) (mass%) alloys are investigated. The corrosion resistance of alloy can be significantly improved by the slight additions of Cu (e.g. 0–2 mass%) without altering either the microstructure or the tensile properties of alloy. On the contrary, alloy with higher addition of Cu, characterized by Cu-rich phases both at grain boundaries and inside the matrix, demonstrates lower corrosion resistance and lower tensile strength. Interestingly, corrosion resistance in grain boundary of alloy gradually increases with Cu content increasing irrespective of the appearance of Cu-rich phases.