A model for predicting grain-boundary energy of refractory high-entropy alloys based on local element concentration

Abstract

Refractory high-entropy alloys (RHEAs) exhibit exceptional high-temperature mechanical properties, and their structural stability is primarily influenced by grain boundaries (GBs). However, it remains challenging to accurately quantify the grain boundary energy (GBE) in RHEAs. Herein, we introduce a quantitative descriptor for point-to-point prediction of GBEs in RHEAs based on local element concentration and valence-electron numbers. Our results demonstrate that the role of the constituent elements on GBEs is primarily determined by their valence-electron numbers in RHEAs. These findings are derived from the cohesive energy and atomic structure of the elements within the framework of the broken-bond model, as well as the differential contributions of s-electrons and d-electrons. The model establishes a structure-property relationship between local element concentration and GBEs, with the prediction consistent with experimental and theoretical results, which is crucial for evaluating the GB stability of RHEAs and facilitating the development of high-performance alloys.