Guaranteed behavior in shape memory alloys. Short- and long-time effects related to temperature and phase coexistence

A phenomenological approach, in the parent phase of Cu-Zn-Al shape memory a lloy, establishes a predictable model (or mathematical equations) relating the dependence of Ms with the temperature over a long period of time (i.e. seasonal or yearly room temperature). High-resolution resistance and temper ature measurements vs. time are used. The long time Ms tracks the external room temperature via two temperature dependent time constants. In steady st ate, the changes in Ms approach 17 per cent of the 'room' temperature chang e. The detailed analysis shows the puzzling disappearance of the after quen ch effects.