Nanocrystallization of a Ti-50.0Ni(at.%) alloy by cold working and stress/strain behavior

Solid state amorphization, crystallization and mechanical properties of an equiatomic Ti-Ni alloy have been investigated by means of differential scanning calorimetry, transmission electron microscopy, thermal cycling tests under constant load and tensile tests. Amorphous phases had domain like shape in the 40% cold rolled alloy, while they had mainly wide band shape in the 70% cold rolled alloy. Crystallization temperature decreased from 552 to 539 K with increasing the amount of cold rolling from 40 to 70%. The average grain size of the 40% cold rolled alloy increased from 27 to 80 nm with increasing annealing temperature from 523 to 673 K. The hysteresis increased rapidly with raising annealing temperature, which was ascribed to an increase in the average grain size. (c) 2006 Elsevier B.V. All rights reserved.