J. Phys. IV France 11 (2001) Pr8-529-Pr8-534
Influence of precipitation and dislocation substructure on phase transformation temperatures in a Ni-rich NiTi-shape memory alloyJ.K. Allafi1, A. Dlouhy2, K. Neuking3 and G. Eggeler1
1 Institut für Werkstoffe IA 1/125, Ruhr-Universität Bochum, 44780 Bochum, Germany
2 Institute of Physics of Materials, AS CR, Zizkova 22, 61662 Brno, Czech Republic
3 Institut für Werkstoffe IA 1/125, Ruhr-Universitat Bochum, 44780 Bochum, Germany
The present work studies the influence of different thermo mechanical treatments on phase transformation and creep of a Ti-50.7at%Ni shape memory alloy. Thermo-mechanically processed, solution annealed, tempered and pre-crept material states show different phase transformation behaviour. Precipitation of Ti3Ni4 particles can rationalize a 20°C increase in phase transition temperatures. Changes of dislocation density and subgrain size also have a systematic but small effect on the martensitic transformation. There is a strong influence of small preloads on the shape of individual creep curves in the early stages of creep which is associated with the precipitation of Ti3Ni4.
© EDP Sciences 2001