Hume-Rothery driven oxidation resilience of binary alloy thin films

Abstract

In metallurgy, Hume-Rothery (HR) rules have proven useful in understanding alloying characteristics and requirements. Recently, they have seen application in the design of multi-principal element alloys (MPEAs), particularly for predicting whether a material combination can form single-phase solid solution high entropy alloys (SSPS-HEAs). However, the HR rules have not been shown to predict the interaction of these alloys with oxides, especially concerning surface and surface chemistry. In this work, we investigate how binary alloys transition from crystalline to amorphous phases at a critical structure dissociation temperature, T1, through in-air stepwise annealing of as-deposited metallic crystalline alloys. At this temperature, sufficient thermal energy enables the alloy to transform into an amorphous oxide phase. By plotting T1 against individual HR rules, we explored the correlation between each rule and the onset of the amorphous phase transition, allowing us to predict the temperatures at which alloys undergo phase changes due to oxidation reactions. These findings demonstrate a relationship between the properties described by the Hume-Rothery and its oxidation resilience (meaning the thermodynamic barrier against oxidation reactivity) in MPEA thin films, offering further fundamental insights into alloy oxidation as a whole.