Fabrication and characterization of a novel β metastable Ti-Mo-Zr alloy with large ductility and improved yield strength

In this paper, a novel ternary β-metastable titanium alloy, Ti-12Mo-5Zr (wt%), was designed based on the “d-electron” alloy design theory. The Ti-12Mo-5Zr alloy displays excellent combination of improved yielding stress (>650 MPa), high ductility (uniform elongation ≈30%) and work-hardening behaviour. The detailed microstructural analysis indicates that the superior performances arise from the synergic effects between phase transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP). Conforming to the design strategy, the improvement of mechanical performance results from the addition of Zr alloying element in substituting Ti, attributing to solution hardening effect and the increasing of critical resolved shear stress (CRSS) of stress induced martensitic transformation (SIM α″). •Ti-12Mo-5Zr alloy exhibits excellent combination of improved yielding strength (>650 MPa), high ductility (uniform elongation ≈30%) and work-hardening behaviour.•The superior performances arise from the synergic effects between phase transformation induced plasticity and twinning induced plasticity.•The ‘d-electron’ alloy design approach in Ti-12Mo-5Zr alloy, i.e. Zr substitution to Ti, validates the feasibility of yielding stress improvement of TWIP/TRIP titanium alloys.