Cryogenic-to-ambient evolution of hetero-deformation-induced strengthening in dual-phase medium-entropy alloys

Ha, H.*; Kim, J.*; Gu, G. H.*; Harjo, S.   ; Gong, W.   ; Hong, S.-J.*; Kim, H. S.*

Ha, H.*; Kim, J.*; Gu, G. H.*; Harjo, S.; Gong, W.; Hong, S.-J.*; Kim, H. S.*

Dual-phase (DP) high- and medium-entropy alloys (H/MEAs), consisting of face-centered cubic (FCC) and body-centered cubic (BCC) phases, have attracted attention because of their excellent strength-ductility balance. However, the temperature dependence of hetero-deformation-induced (HDI) strengthening remains unclear. In this study, an Al(CoNiV) DP MEA was investigated using in-situ neutron diffraction and multiscale electron microscopy. Both intrinsic strength and HDI strengthening increased at cryogenic temperature. This enhancement originated from the increased lattice friction stress of the hard BCC phase and suppressed dislocation mobility at low temperature, which promoted dislocation accumulation at heterogeneous interfaces. These findings provide insights into temperature-dependent HDI strengthening in DP H/MEAs and related alloy systems.