Third element diffusion induced amorphization of NiTi in a NiTi-Nb nanocomposite

The paper reports a unique and rare phenomenon observed in a NiTi-Nb nanowire in-situ composite system. The phenomenon is the amorphization of the B2 NiTi matrix caused by the diffusion of Nb through the B2 lattice. The diffusion of Nb through the NiTi matrix is driven by the effect of Oswald ripening associated with the fragmentation and granulation of Nb nanowires at elevated temperatures and the amorphization of the NiTi matrix is attributed to the effect of Ni-Ti atomic swapping, i.e., the formation of anti-site defects in the B2 structure, caused by the substitutional diffusion of a third element, Nb in this case. The phenomenon is observed by transmission electron microscopy examination and x-ray diffraction measurement and the hypothesis of explanation is supported by molecular dynamic simulation studies.

Automated summary

The paper presents a unique phenomenon observed in a NiTi-Nb nanowire in-situ composite system, where the B2 NiTi matrix undergoes amorphization due to the diffusion of Nb through the B2 lattice. The diffusion of Nb in the NiTi matrix is driven by Oswald ripening, which occurs during the fragmentation and granulation of Nb nanowires at elevated temperatures. The amorphization of the NiTi matrix is attributed to the formation of anti-site defects caused by the substitutional diffusion of Nb.