Breaking the strength-ductility paradox in advanced nanostructured Fe-based alloys through combined Cu and Mn additions

The strength-ductility paradox is a long-sought challenge for all engineering materials. In this study, we escaped the strength-ductility trade-off by engineering nano-scale heterogeneities carefully in the advanced nanostructured Fe-based alloys through alloying with Cu and Mn additions. We demonstrated a triple ductility enhancement by 20% together with a strength improvement of 100MPa compared to the alloys with sole Cu additions, overturning a common understanding of the strength-ductility trade-off. The strength-ductility enhancement is attributed to the complex interplay between the transformation induced plasticity (TRIP) and the coherent nano-scale Cu precipitates as well as the resultant heterogeneous stress-strain partitioning and dislocation interactions. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.