Characteristics of the two-way memory effect induced by thermomechanical cycling in Cu-Zn-Al single crystals

Some results concerning the two-way shape memory effect induced by thermomechanical training in Cu-Zn-Al single crystals with e/a=1.48 are presented. The repetitive training procedure consists of a thermal induced transformation with the specimen submitted to a constant tensile stress and a subsequent reverse transformation without any external applied stress. The induced two-way shape memory effect is characterized by measuring the efficiency and the strength, cooling the sample under a compressive external stress. Some specimens are conveniently thermally treated in order to introduce dispersions of small gamma-phase precipitates (size about 10 nm) inside the beta matrix. The characteristics of the two-way memory effect shown by the material containing precipitates and the precipitate-free alloy are compared.