The temperature memory effect and the influence of thermo-mechanical cycling in shapememory alloys

Abstract

Apart from the well-known shape memory effect (SME), the temperature memoryeffect (TME), i.e., the ability of a material to remember the heating interruptedtemperature in the previous thermal cycle, is another interesting phenomenon observed inmany shape memory alloys (SMAs). In this paper, based on previous and currentexperimental observations, we propose a phenomenological model to reproduce theTME. Subsequently, we study the influence of thermo-mechanical cycling (uniaxialtension) on the TME in a polycrystalline NiTi SMA wire (0.51 mm diameter).The maximum tensile strain in each cycle is 10%, which is beyond its elasticlimit. The evolution of the peak transition temperature in the forward and reversetransformations and the TME upon thermo-mechanical cycling is investigated bydifferential scanning calorimetry. It is proved that the TME is a stable intrinsicphenomenon and can be utilized even under severe thermo-mechanical conditions.