Mechanical properties and microstructures of β Ti-25Nb-11Sn ternary alloy for biomedical applications

The mechanical properties and microstructures of 13 Ti-25%Nb-11%Sn ternary alloy rods were investigated for biomedical applications as a function of heat treatment temperature after swaging by an 86% reduction in cross-section area. An as-swaged rod consisting of a beta (bcc) single phase shows a low Young's modulus of 53 GPa, which is interpreted in terms of both the metastable composition of the beta alloy undergoing neither an athermal omega transformation nor a deformation-induced to transformation and < 110 > texture development during swaging. Heat treatment at 673 K (400 degrees C) for 2 h leads to a high strength of approximately 1330 MPa and a high spring-back ratio of yield stress to Young's modulus over 15 x 10(-3), with acceptable elongation. This high strength is attributable to needle-like a precipitates, which are identified by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and high-resolution electron microscopy (HREM). (C) 2013 Elsevier B.V. All rights reserved.