Wavy interface enables extra strengthening in an additively manufactured high-entropy alloy with Mortise-Tenon architecture

Abstract

Laminated structures have the potential to enhance the performance of high-entropy alloys (HEAs) by providing intriguing interface strengthening. However, laminated HEA designs is uncommon due to the challenges posed by the relatively poor machinability of HEAs. In this study, we successfully fabricate a CoCrNi-Fe50Mn30Co10Cr10 laminated HEA using additive manufacturing technique, incorporating a unique Mortise-Tenon architecture within the alloy. The laminated HEA introduces a novel wavy-shaped interface alongside the conventional flat-shaped interfaces. Tensile tests reveal that the laminated HEA exhibits an exceptional combination of strength and ductility. The measured yield strength exceeds the predicted value based on the rule-of-mixture principle by approximately 36.5 %. This enhancement is attributed to the extra strengthening resulting from the local chemical variation near the heterogeneous interfaces. Interestingly, the wavy-shaped interface has a larger local-chemical-variation zone than the flat-shaped interface, which can trigger more strong interface-dislocation interactions and therefore remarkable strengthening. The Mortise-Tenon architecture not only provides extra interface strengthening, surpassing the yield strength of the two monolithic HEAs, but also preserves the excellent work hardening ability in the early stage of deformation, enabling reasonable ductility. Remarkably, the interface strengthening is comparable in magnitude to dislocation strengthening, contributing to approximately 23 % of the overall yield strength. These findings highlight the potential of laminated HEA designs and the associated interface strengthening as promising strategies for enhancing mechanical performance.