Martensitic twinning transformation mechanism in a metastable IVB element-based body-centered cubic high-entropy alloy with high strength and high work hardening rate

Realizing high work hardening and thus elevated strength–ductility synergy are prerequisites for the practical usage of body-centered-cubic entropy alloys (BCC-HEAs). In this study, we report a novel dynamic strengthening mechanism, martensitic twinning transformation mechanism in metastable refractory element-based BCC-HEA (TiZrHf)87Ta13 (at.%) that can profoundly enhance capability, leading to large uniform ductility strength simultaneously. Different from conventional induced plasticity (TRIP) (TWIP) mechanisms, combines best characteristics both TRIP TWIP which greatly alleviates strength-ductility trade-off ubiquitously observed BCC structural alloys. Microstructure characterization, carried out using X-ray diffraction (XRD) electron back-scatter (EBSD) shows that, upon straining, α” (orthorhombic) martensite transformation, self-accommodation (SA) mechanical were activated sequentially. Transmission microscopy (TEM) analyses reveal continuous activation is inherited nucleating {351}α” type I twins within SA ‘‘{351}’’<2¯11>α” II twinned variants on plane by through simple shear, thereby accommodating excessive plastic strain shear while concurrently refining grain structure. Consequently, consistent rates 2–12.5 GPa achieved during entire deformation, tensile 1.3 elongation 24%. Alloy development guidelines activating such proposed, could be important developing new BCC-HEAs with optimal performance.