Shape memory effect in a Cu–Zn–Al alloy with dual phase α/β microstructure

The paradoxical decrease of the one way (OWSME) and the two-way shape memory effect (TWSME) with increasing volume fraction of martensite in dual phase microstructure obtained by quenching from dual phase equlibrium field α/β in a Cu–Zn–Al alloy presented at Icomat ’95 is re-evaluated. It is also found that TWSME degradation by thermal cycling increases with decreasing volume fraction of martensite. Both phenomena are accompanied by changes in degree of order in martensite, solution hardening of the α-phase and the stacking fault energy of martensite. They seem to be caused by the synergetic effect of changes in the stacking fault energy of martensite and solid solution hardening of the α-phase.