Abstract: High entropy alloy is a new type of atom-ordered and chemically disordered alloy with multi-principal elements, which can obtain outstanding comprehensive mechanical properties, because that by changing the type and concentration of alloying elements, the stacking fault energy and phase stability of alloys can be controlled, then inducing deformation twins, martensitic transformation and other plastic deformation mechanisms. The design concept of such high entropy alloys is called “metastable engineering”, and the microstructure, phase structures and deformation mechanisms of high entropy alloys are closely related to stacking fault energy of the alloy system. For the FeMnCoCr system, the phase stability of face-centered cubic structure decreases with the decreasing of stacking fault energy, and so the interface hardening and the transformation induced hardening (γ→ε) are introduced, improving the strength and plasticity of the alloy simultaneously. The composition design, preparation and processing method, microstructures and mechanical properties of the FeMnCoCr metastable high entropy alloys are reviewed here, and its future research direction is prospected.

Key words: high-entropy alloy, transformation induced plasticity, stacking fault energy, mechanical properties