Synergistic effects of short-range order and amorphous/crystalline interface on the mechanical behavior of high-entropy alloys

The strength-ductility trade-off in high-entropy alloys (HEAs) remains a critical challenge limiting their practical applications. The synergistic regulation of amorphous/crystalline interfaces (ACIs) and short-range order (SRO) offers a promising strategy to address this dilemma. In this study, the effects of ACI, SRO, and their coupling on the mechanical behavior of HEAs containing either high-angle grain boundaries (HAGB models) or ACIs (ACI models) are systematically investigated using hybrid molecular dynamics and Monte Carlo simulation methods. The results reveal that the introduction of ACIs reduces the yield strength of the HAGB models and diminishes their sensitivity to crystal orientation, shifting the dominant yielding mechanism from orientation-dependent dislocation slip to the activation of shear transformation zones within the amorphous phase. The introduction of SRO increases the yield strength of both the ACI and HAGB models, with a more pronounced strengthening effect observed in the ACI models. This strengthening also exhibits sensitivity to crystal orientation, further confirming the significant strengthening role of SRO. Notably, the strengthening effect of SRO does not increase monotonically with the degree of SRO; instead, it initially rises and subsequently exhibits a non-monotonic evolution. Furthermore, the microscopic mechanisms of individual interactions between dislocations and ACIs, as well as between dislocations and SRO are systematically analyzed. These findings provide important theoretical guidance for achieving synergistic strengthening through ACIs and SRO, thereby enabling the design of HEAs with both high strength and high ductility.