Strong and ductile beta Ti-18Zr-13Mo alloy with multimodal twinning

Body-centred cubic (BCC) Ti-18Zr-13Mo (wt%) alloy displays excellent yield strength (approximate to 800 MPa), stable hardening (rate>1500 MPa) and uniform ductility >18%, resulting from multi-TWIP (multiple twinning-induced plasticity) strengthening effect. This multimodal mechanisms include micro-scale {332}<113> deformation twinning (DT), nano-scale {112}<111> DT and a rare {5 8 11}<135> DT mode. Martensitic phase transformation is completely suppressed and the sample stays a single-phase solid solution throughout the deformation. In situ electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) were used to characterize the multi-TWIP and dynamic Hall-Patch effect, with dislocation slip and large grain distortions at twin interfaces. IMPACT STATEMENTThe addition of Zr solutes stabilizes Ti-alloy and completely suppresses phase transformations, allowing {332}<113>, {112}<111> and {5 8 11}<135> multimodal twinning to give a better combination of strength, strain-hardening rate and ductility. [GRAPHICS]