Stabilization and two-way shape memory effect in Cu-Al-Ni single crystals

The two-way shape memory effect (TWME) induced by stabilization of the mart ensite phase during aging has been studied in Cu-13.4 Al-4.0 Ni (mass pet) single crystals. The influence of the degree of long-range order on the tra nsformation has been determined by using different heat treatments. The tra nsformation temperatures are strongly influenced by the degree of order in the austenite: annealing from above or below the second neighbor L2(1) orde ring temperature changes the M-s by more than 100 degrees C. It has been es tablished that the diffusion in the austenite as well as in the martensite phase is considerably slower in this alloy than in other Cu-based ones, due to the presence of Ni. The obtained TWME has a similar efficiency as when other more complex thermomechanical trainings are made. In this alloy, the TWME by stabilization is not complete, in contrast to that in Cu-Zn-Al sing le crystals.