Structure and Shape Memory Effect in Annealed Ni-Ti-Co Strip Produced by Twin Roll Casting Technique

摘要

The ternary Ni_(47)Ti_(50)CO_3 alloy was produced using twin rolls casting technique. The strip was annealed at 300℃, 400℃ or 500℃ for 1 hour. Annealing was carried out in real condition without protection atmosphere. The strips revealed a multi-stage martensitic transformation. However, the origin of this multi-stage transformation is different in the as-cast strip when compare to the thermally treated samples. Thermal treatment increases amount of preferentially oriented grains and in consequence higher degree of the shape recovery can be obtained.