The evolution of Ti₂Ni precipitates in annealed Ti₅₁Ni₄₉ shape memory melt-spun ribbons

Abstract

Guinier–Preston (GP) zones are observed in as-spun and 200/350°C annealed Ti-rich Ti₅₁Ni₄₉ ribbons. For ribbons annealed at 350–600°C for 1 h, nanosized Ti₂Ni precipitates with Moiré fringes are observed and the spacing of the Moiré fringes increases with the increase of annealing temperature. The analysis of Moiré fringes spacing indicates that Ti-deficiency and equilibrium Ti₂Ni precipitates form in ribbons annealed at 350/400°C and at 500/600°C, respectively.

Keywords:

• melt spinning
• shape memory alloys
• annealing
• precipitation
• transmission electron microscopy

Acknowledgements

The authors gratefully acknowledge the financial support for this research by the National Science Council (NSC), Taiwan, Republic of China, under the grant no. NSC97-2221-E002-035-MY3.