Chemical short-range order in complex concentrated alloys

Complex concentrated alloys (CCAs) have drawn immense attention from the materials research community and beyond. Because the vast compositional and structural degrees of freedom in CCAs can lead to novel properties (e.g., structural and functional) with a wide range of applications, the structure–property relationships of CCAs are of critical interest. One salient feature in the atomic structures of CCAs is the presence of chemical short-range ordering (CSRO). Understanding the roles of CSRO on properties, especially phase stability, requires joint efforts from experimental and computational approaches. In this article, we first briefly survey the most recent experimental efforts in identifying and characterizing CSRO of various CCAs. We then focus on the theoretical and computational techniques that have been deployed to investigate the CSRO effects. These computational methods include density functional theory (DFT), molecular dynamics (MD), and statistical mechanics methods such as cluster expansions and machine learning methods such as creating transferable interatomic potentials. Finally, we outline the challenges and future directions of CSRO research in CCAs.