Micro and macroscopic effects on the long time guaranteed behaviour of Cu-based shape memory alloys

From high-resolution measurements of electrical resistance and transformation temperatures of Cu-based shape memory alloys, it has been possible to formulate predictive models for the long time behaviour of the material (transformation temperatures) near room temperature, as a function of time and temperature. With the help of the time scales obtained with mesoscopic measurements, the microscopic origin of the long time evolutive processes has been looked for single crystal X-ray diffraction on CuZnAl, and the existence of significant room temperature diffusive long range ordering of atomic species has been found. (C) 2004 Elsevier B.V. All rights reserved.