Crystallographic analysis and phase field simulation of transformation plasticity in a multifunctional β-Ti alloy

The gum-like multifunctional beta-Ti alloy Ti-24Nb-4Zr-8Sn-0.100 (in wt.%), known as Ti2448, has attracted a lot of attention lately for promising biomedical applications due to its ultralow apparent elastic modulus, high strength, super-elasticity, strong fatigue resistance, and excellent biocompatibility. In this study we investigate the deformation mechanisms in association with martensitic transformation (MT) in the alloy. Using a combination of crystallographic analysis and phase field simulation we find a rich variety of strain-accommodating domain patterns, including 30 twinning modes and 6 herringbone structures. These diverse strain accommodating modes, especially the excellent geometrical compatibilities of the twins and herringbone structures, provide the MT with great flexibility to adapt to arbitrary shape changes and defect structures generated during plastic deformation, which may have contributed to the exceptional mechanical properties of the alloy. (C) 2016 Elsevier Ltd. All rights reserved.