THERMAL ARREST MEMORY EFFECT

The course of the martensitic transformation is affected by strain fields in the untransformed parent phase. One of the consequences of this in Ni-Ti shape memory alloys is the ''Thermal Arrest Memory Effect'' (TAME), where the martensite to parent phase transformation ''remembers'' the temperature of arrest in the previous thermal cycle. From the results of the calorimetric investigations in this study, it is deduced that the TAME is the result of locked-in transformation strain energy in the self-accommodating martensitic microstructure. Thus it is found that on account of the large difference in the degree of self-accommodation achieved in the martensitic microstructures, TAME is observed to be significant in Ni-Ti and not in Cu-Zn-Al shape memory alloys.