Atomic-Scale Measurement of Chemical Short-Range Order (C-SRO) in CrMnFeCoNi High Entropy Alloys and Its Effect on the Deformation Behaviors

Since high entropy alloy (HEA) is constituted with multi-principal elements, it can be understood in a very severe condition of solid solution strengthening (SSS). In particular, the short-range order (SRO), sub-nano scale atomic structure, can be easily formed in HEAs. Understandably, the SRO can drive HEAs to extreme conditions of SSS.<br/>The SRO can be classified into two different ones: topological (T) and chemical (C) SRO. Since the T-SRO has a different crystallographic property with the matrix, it can be easily measured. However, it is far more difficult to measure the C-SRO, because it is the only cluster of a few atoms having preferential bonding among specific elements with thermodynamic stability.<br/>In the present study, we systematically evaluate the influence of C-SRO formation on the degree of SSS in various CrMnFeCoNi HEAs. The SRO formation was carefully controlled by solidification history intensive structural analysis, including APT, EXAFS, and so on. Finally, this work will establish a tuning recipe for SSS in HEAs, which uses the sub-nano scale structural information.