RELAXATION IN SHAPE-MEMORY ALLOYS .2. THERMOMECHANICAL MODEL AND PROPOSED EXPERIMENTS

A variety of relaxation phenomena such as stabilization of martensite, rubber-like behavior, evolving hysteresis loops and stabilization of interfaces have been observed in various shape-memory alloys. These ef fects adversely impact technological applications. In Part I of this p aper we proposed a phenomenological, but predictive, model of the mech anical behavior of these materials. We showed that this model reproduc es the experimental observations. In this part, we extend this model t o include the effects of temperature and the austenite-martensite tran sformation. Once again, the predictions from this extended model agree with experimental observations. We can therefore conclude that the ba sic phenomenological ideas combined with a few easily measured materia l parameters is sufficient to predict the behavior of these materials. Finally, we propose new experiments in order to probe longstanding is sues concerning the mechanism responsible for the relaxation. (C) 1997 Acta Metallurgica Inc.