Enhanced cryogenic tensile properties with multi-stage strain hardening through partial recrystallization in a ferrous medium-entropy alloy

We demonstrate the formation of partially recrystallized bimodal microstructures through single-step heat treatment after cold-rolling in Fe60Co15Ni15Cr10 (at%) ferrous medium-entropy alloy that leads to the enhanced yield-strength of similar to 1.1 GPa and ultimate-tensile-strength of 1.7 GPa at persistent ductility of 61%, evading strength-ductility trade-off. The retention of deformation substructures allows a yield-strength increase by similar to 79% compared to that in a fully-recrystallized state, together with the modification of mechanical stability without compositional variation, resulting in multi-stage strain hardening capability during tensile deformation at 77 K. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, we demonstrate the formation of partially recrystallized bimodal microstructures in the Fe60Co15Ni15Cr10 (at%) ferrous medium-entropy alloy through a single-step heat treatment after cold-rolling. This process enhances the yield-strength and ultimate-tensile-strength of the alloy while maintaining a persistent ductility of 61%, thus avoiding the strength-ductility trade-off. The retention of deformation substructures allows for a significant increase in yield-strength compared to a fully-recrystallized state.