SUPERELASTICITY AND SHAPE-MEMORY EFFECT IN CU-23AT-PERCENT-AL-7AT-PERCENT-MN ALLOY SINGLE-CRYSTALS

Stress-strain behavior associated with the thermoelastic martensitic transformation in Cu-23at.%Al-7at.%Mn is studied using single crystals oriented the [001] direction. Shape memory effect and superelasticity are observed at a certain temperature range, and the multi-stage stress-strain curve due to successive stress-induced transformation has been found. This mechanical behavior is essentially identical to those of a Cu-Al-Ni alloy. However, owing to large dissipative force for the parent to gamma1', transformation, the stress-induced transformation which differs from that expected from the equilibrium phase diagram is observed. This results in an intermediate stress-strain behavior which has not been observed in the Cu-Al-Ni alloy.