Corrosion of a non-equimolar multi-principal element alloy containing 13 at% Ru after aging

A non-equimolar multi-principal element alloy of composition Ni38Cr21Fe20Ru13Mo6W2 (referred to as MPEA1) designed from the perspective of corrosion resistance has been recently reported. Single-phase MPEA1 possesses excellent resistance to general and localized corrosion even in extremely aggressive environments. Annealing solutionized single-phase MPEA1 at 1073 K for 160 h resulted in the precipitation of a plate-like σ-phase rich in Cr, Ru, Mo and W. Like the single-phase MPEA1, the heat-treated multi-phase form of the alloy was found to be immune to localized corrosion at ambient temperatures and did not pit in 0.6 M NaCl up to 80 °C.