Interstitial-Free Bake Hardening Realized by Epsilon Martensite Reverse Transformation

Abstract

By investigating a metastable high-entropy alloy, we report a latent strengthening mechanism that is associated with the thermally-induced epsilon-martensite-to-austenite reverse transformation. We show this reversion-assisted hardening effect can be achieved in the same time-scale and temperature range as conventional bake-hardening treatment, but leads to both improved strength and cumulative ductility. Key mechanisms are discussed considering transformation kinetics, kinematics, strengthening and ductilization modules.