Mechanistic insights into selective oxidation and corrosion of multi-principal element alloys from high resolution and in situ microscopy

Abstract Multiple principal element alloys (MPEAs) have drawn significant recent interest from the metallurgical research community. These novel alloys have the potential to replace traditional alloys with a range of tailored mechanical properties, corrosion resistance, and radiation tolerance enabled by complex compositions. The broad alloy design space of MPEAs presents a great opportunity to discover new forms of oxidation and corrosion resistance in extreme environments that break away from conventional alloy design criteria. However, understanding the oxidation and corrosion response of MPEAs can be a challenging task due the complex compositional, structural, and chemical state changes occurring in the oxide or corrosion film and at its interface with the base alloy. This perspective discusses the utility of high resolution and in situ microscopy techniques for revealing unique aspects of MPEA oxidation and corrosion behavior at the atomic and near atomic scales. Challenges of studying oxidation and corrosion response of these alloys and several open questions are presented.