Strong room temperature work hardening in a dual heterogeneous structured ferrous medium entropy alloy

In this work, a novel (Fe65Ni15Cr10Co10)92Ti5Al3 medium-entropy alloy (MEA) with a dual heterogeneous structure was produced by adding Ti and Al in our previous reported Fe65Ni15Co10Cr10 MEA. The dual hetero-geneous structure consists of the partial recrystallization matrix and heterogeneous nanoprecipitates. The tensile tests show that the MEA displays an ultra-high ultimate tensile strength (1519 MPa) and work hardening extent (559 MPa) at room temperature. The addition of Ti and Al produces precipitates while lowering FCC stability. This contributes to a continuous FCC -> BCC martensitic transformation and a consequent transformation-induced plasticity (TRIP) effect during whole plastic deformation. Therefore, the excellent mechanical properties are attributed to the synergism of multiple mechanisms, including the hetero-deformation induced (HDI) strength-ening, precipitation strengthening, and TRIP effects. The alloy design strategy in this paper has guiding signif-icance for the development of high-performance ferrous MEAs.

Automated summary

In this study, a novel medium-entropy alloy (MEA) (Fe65Ni15Cr10Co10)92Ti5Al3 with a dual heterogeneous structure was developed by adding Ti and Al to a previously reported Fe65Ni15Co10Cr10 MEA. The MEA exhibited ultra-high ultimate tensile strength and work hardening extent at room temperature. The addition of Ti and Al induced precipitation and resulted in a continuous FCC -> BCC martensitic transformation and a transformation-induced plasticity effect. The excellent mechanical properties of the alloy were attributed to the synergistic effects of hetero-deformation induced strengthening, precipitation strengthening, and TRIP.