| Abstract Scope |
Multi-principal element alloys (MPEAs), also known as high entropy alloys (HEAs), have been widely researched since their initial development by Cantor, et al. Recently, refractory MPEAs have begun to garner more attention due to their exceptional high temperature mechanical properties. However, it is well known that the performance of refractory MPEAs at elevated temperatures is limited by oxidation. Improving the phase stability of MPEAs—both internally (i.e. suppressing intermetallic formation) and externally (i.e. oxidation)—is crucial to enabling their use in high temperature applications. In this work, the onset of oxidation in pure W and MoNbTaW is studied by leveraging multi-scale characterization techniques (e.g. SEM, TEM, XRD, nanoindentation, and in-situ micro-tensile testing) to observe microstructural and mechanical changes in sputtered films before and after low-temperature annealing in air. Through understanding of the initial stages of oxidation, the alloy chemistry can be tailored to improve phase stability in extreme environments. |