Direct experimental evidence for the non-linear elasticity of multi-functional alloy Ti2448

The ageing of human bone leads to bone diseases and the functional failure of joints. Joint replacement is effective in relieving paints and recovering functions. The mechanical properties of materials determine the performance of artificial replacements. The newly developed Ti2448 (Ti–24Nb–4Zr–8Sn-0.13O, wt.%) possesses excellent mechanical properties, especially its low modulus. Usually, metals show linear elasticity, complying with the Hooke's law. However, Ti2448 exhibits a special non-linear elastic deformation behavior, which is in contrast to most metals. While, deformation mechanisms underpinning this special non-linear elasticity is still unclear although extensive effort has been made in recent years. In this study, direct experimental evidences of stress-induced β→α″ martensitic transformation are obtained by employing in situ XRD and high-resolution transmission electron microscopy. It is found that martensitic transformation is the physical origin of the non-linear elasticity of Ti2448. The findings of this study shed light on understanding and further optimizing mechanical properties of Ti2448 and other multifunctional shape memory alloys.