Achieving a combination of decent biocompatibility and large near-linear-elastic deformation behavior in shell-core-like structural TiNb/NiTi composite.

As expected from the material design, a novel shell-core-like structural TiNb/NiTi composite possessing both decent biocompatibility and large near-linear-elastic deformation behavior (namely as near-linear elasticity accompanied by high elastic strain limit) was prepared successfully by a hot pack-rolling combined with cold rolling procedure. Non-cytotoxic TiNb outer shell obstructs the NiTi inner core from cells and provides the decent biocompatibility of TiNb/NiTi composite. Large near-linear-elastic deformation behavior for this TiNb/NiTi composite has been confirmed to be associated with intrinsic elastic deformation, two types of reversible stress-induced martensitic transformations (i.e. ß↔α'' and B2↔B19' transformations) occurring in a homogeneous manner, together with the (001) compound twin in B19' martensitic plates. Our study provides a new design approach for developing NiTi-based composites with both decent biocompatibility and large near-linear-elastic deformation behavior for biomedical or engineering applications.