A study of the structure of G-P zones in Ti-rich TiNi shape memory melt-spun ribbons

Abstract

A hybrid structure composed of ordered C11_b Ti₂Ni and Ti₅Ni₃ substructures for the G-P zones precipitated in Ti-rich Ti–Ni shape memory ribbons is proposed to explain the appearance of extra diffuse scattering streaks in transmission electron microscopy observations. The point defects of Ni vacancies and Ti antisites, resulting in the lattice fluctuant displacement, also cause the incommensurate extra diffuse scattering streaks.

Keywords:

• shape memory alloys
• Guinier-Preston zones
• microstructure
• transmission electron microscopy

Acknowledgements

The authors gratefully acknowledge the financial support for this study provided by the National Science Council (NSC) and National Taiwan University (NTU), Taiwan, under Grants NSC100-2221-E-002-100-MY3 and NTU 101R891803, respectively. They also sincerely acknowledge the assistance of Professor H. Kimura at the Institute for Materials Research, Tohoku University, Japan, for assistance in ribbon preparation.