Effect of Hf addition on microstructural evolution and corrosion behavior of nickel-based alloys in hydrochloric acid

Abstract

The effect of hafnium (Hf) addition on microstructural evolution and corrosion behavior of nickel-based alloys was investigated. The findings indicated that adding Hf appropriately can increase the ratio of Cr2O3 and O2- species in the passive film, resulting in a greater resistance to localized corrosion. However, microgalvanic coupling occurred when precipitates were present in Hf0.5 and Hf1.0 alloys, with the face-centered cubic matrix acting as cathode and Hf-rich precipitates serving as anodes, leading to a preferential corrosion of the latter and a subsequent reduction in the corrosion resistance of the nickel-based alloys.