Generation and stability of reversible shape change in NiTi memory alloys

Shape Memory Alloys (SMA) are promising materials for actuator components. This work focuses on the principal aspects underlying the deformation phenomenon known as Two-Way Shape Memory Effect (TWSME). On wire specimens of a near equiatomic NiTi alloy such an effect is achieved by a thermomechanical treatment. Depending on the training parameters and heat treatment conditions, different magnitudes of reversible shape change are obtained. Further experimental work concentrates on the stability of this special effect throughout cyclic application. Again a strong influence of the initial microstructure on the degradation characteristic is observed.