New Findings on the Cryogenic TWIP Effect in Ti-3Al-2Zr-1.5Mo Alloy with Lamellar Microstructure

Quasi-static tensile deformation behaviors at room temperature (RT) and 77 K of Ti-3Al-2Zr-1.5Mo alloy with lamellar microstructure were systematically investigated in this study. The experimental results indicated the excellent cryogenic mechanical properties of Ti-3Al-2Zr-1.5Mo alloy with lamellar microstructure. The strength and elongation of the Ti-3Al-2Zr-1.5Mo alloy at 77 K are much larger than those of RT specimen. It demonstrated that the strength, plasticity and strain-hardening rate were improved simultaneously at cryogenic temperature. Microstructural analysis indicated that strong cryogenic twinning induced plasticity (TWIP) effect occurs in the Ti-3Al-2Zr-1.5Mo alloy with lamellar microstructure. The intersection between the substructure and the α/β interface is one of factors to the nucleation of twins at cryogenic temperature. The optimization of the properties of Ti-3Al-2Zr-1.5Mo alloy should be attributed to the significant TWIP effect at cryogenic temperature. In addition, the cryogenic environment weakens the hindering effect of the interfaces on crack propagation.