From dual-shape/temperature memory effect to triple-shape memory effect in NiTi shape memory alloys

摘要

Triple-shape memory effect (SME), i.e., to recover the original shape through one intermediate shape upon heating, has been demonstrated as an intrinsic feature of thermo-responsive shape memory polymers (SMPs) after being uniformly programmed, but seemingly has yet been achieved in shape memory alloys (SMAs). In this paper, we study two programming approaches, in which the deformation is uniform throughout the whole sample length without involving any permanent change in material properties at all, to realize the triple-SME in NiTi SMAs. We show that the triple-SME can be tailored to meet the temperature/strain requirements. With this technique, now we are able to achieve step-by-step motion control in SMAs.