Isothermal B2-B19' martensitic transformation in Ti-rich Ni-Ti shape memory alloy

摘要

The athermal/isothermal nature of the B2<->B19' martensitic transformation was investigated by means of electrical resistance measurements in a Ni_(49.5)Ti_(50.5) alloy that has elevated transformation temperatures as compared with the near-equiatomic or Ni-rich compositions studied previously. The direct B2-B19' martensitic transformation shows a clear time dependence, whereas isothermal effects are not revealed for the reverse B19'-B2 transition. The applicability of the C-shaped time-temperature-transformation diagram to interpret the experimental results is discussed.