FROM ADAPTED AND COMPUTERIZED THERMOMECHANICAL EQUIPMENTS TO MODELINGAND THE TIME-EVOLUTION BEHAVIOR IN CU-ZN-AL SHAPE-MEMORY ALLOYS

Using two similar high resolution computer controlled stress-strain-te mperature set-up of equivalent resolution (1 mN, 0.1 mum, 5 mK) the de tailed study of the martensitic transformation in single crystals of t he Cu-Zn-Al shape memory alloys is realized. The devices can obtain 20 or 150 N in applied force, 2 or 4 mm in length and can be operated ne ar room temperature (between 280 and 360 K). The analysis of the hyste resis domain in single crystals clearly visualises the intrinsic chara cteristics of the material (pseudoelasticity, nucleation, interface fr iction) and enables the obtention of parameters for physical models of the hysteretic behaviour in force - lengthening - temperature and, ev entually, time-dependent processes. The observation of time evolution shows the 'recoverable martensite creep' associated to a microstabiliz ation process.