Microstructural evolution and its influence on the mechanical properties of a thermomechanically processed β Ti–32Zr–30Nb alloy

Abstract

In this study, microstructural evolution and its influence on the mechanical properties of a newly developed titanium–zirconium–niobium (TZN) alloy after cold rolling and recrystallization annealing have been investigated. With an increase in the cold rolling reduction rate (CRRR) of the Ti–32Zr–30Nb TZN alloy, a change in the plastic deformation mechanisms has been observed. Deformation-induced α” and kink bands were observed in the TZN alloy after cold rolling at 20% and 56% CRRR; however, with a further increase in CRRR, while the deformation mechanisms including kink bands, {332} <113> β mechanical twinning and shear bands were increased, the formation of deformation-induced α” was suppressed. The Young's modulus of the TZN alloy specimen after cold rolling at 86% CRRR was found to be higher than those of the specimens after cold rolling at 20%, 56% and 76% CRRR, due to the reverse transformation of the deformation-induced martensite α” into β. The TZN alloy is evaluated as a promising candidate material for orthopaedic implant applications by virtue of its unique combination of values for Young's modulus, tensile strength, elongation at rupture and elastic admissible strain, which were measured in the ranges of 57–69 GPa, 692–961 MPa, 4–10% and 1.11–1.31%, respectively, after various thermomechanical treatments.