Enhanced corrosion rate for Mg-xEr-1.6Ni alloys with high Er content by regulating the second phase via short-time low-temperature heat treatment

Abstract

The effects of the high content of erbium (Er) addition (9.5–17 wt%) and short-time low-temperature heat treatment on the microstructure evolution, corrosion behaviors and mechanism of Mg-xEr-1.6Ni alloys have been investigated. After heat treatment, the corrosion rate for various Er content alloys increased by 15.1–338.8% in comparison to as-cast alloys, which was mainly related to the formation of Er-rich phases and the increase the density of laminar γ′ phase. These phases increase the galvanic coupling pairs and provide more corrosion propagation paths, reducing the Er content in the Mg matrix and weakening the corrosion barrier.