Superelastic effect in Ti-rich high entropy alloys via stress-induced martensitic transformation

This letter reports an outstanding superelastic effect in Ti-rich TiZrHfAlNb high entropy alloys for the first time, which is exhibited by comprehensive combination of the maximum total recovery strain, fully recoverable strain and corresponding tensile strength up to 5.2%, 4.0% and 900 MPa, respectively. It has been confirmed that these alloys are only composed of metastable β and martensite α″ phase, and ω phase is suppressed. The in situ X-ray diffraction experiment reveals that reversible stress-induced martensitic transformation between β ↔ α″ endows the alloys superelasticity, while the plastic deformation and reorientation of martensite inhibit the recovery phase transformation.