Diffusion effects on transformation and deformation behavior in copper-based shape memory alloys

Experimental mesoscopic observations of the parent phase ill Cu-based shape memory alloys. the associated martensitie transformation and the corresponding hysteresis cycle, are carried out. The coexistence effects between martensite and parent phase and file evolution of the transformation temperature (M-s). due to yearly effect on the parent phase, are determined. Several of years of continuous measurements, mainly using Cu-Zn-Al alloys. establish: (A) The evolution of the transformation temperature with time and temperature in parent phase (amplitude close to 15% of the ambient temperature change). (B) The changes related with the coexistence among the phases (close to 5 K). (C) The existence of remnant after quench effects are also partially visualized via neutron diffraction. A model based oil the experimental results describes the hysteresis cycle and the internal loops. The diffusion effects can be included in the model and the time evolution of Ms and of the hysteretic behavior can be well established. The simulated results allow predicting the damping performance of the material for long-term actions.