Metastability-assisted fatigue behavior in a friction stir processed dual-phase high entropy alloy

Metastability-based high entropy alloy design opens a new strategic path for designing high-strength materials. However, high strength is always coupled with poor damage tolerance under cyclic loading conditions (fatigue). To overcome this drawback, here we present grain-refined Fe42Mn28Cr15Co10Si5 exhibiting significantly high fatigue strength as compared with leading transformation induced plasticity steels upon friction stir processing. The enhanced fatigue behavior is attributed to the metastability-promoted E transformation that caused local variation in work-hardening activity near the crack tip, and subsequent crack branching. Thus, decreased phase stability assisted not only in attaining strength but also in making the alloy fatigue-resistant. [GRAPHICS] Impact StatementFatigue resistance of dual-phase TRIP Fe42Mn28Cr15Co10Si5 was evaluated. Metastability-promoted E transformation improved fatigue life due to local enhancement in work-hardening near the crack tip.