Spinodal decomposition and martensitic transformation in Cu–Al–Mn shape memory alloy

Abstract

Isothermal treatments at 413 K were performed in Cu–Al–Mn shape memory alloy samples, to study their effects on the martensitic transformation. This procedure, within the miscibility gap, produces spinodal decomposition. After each aging thermal treatment, martensitic transformation was monitored using Differential Scanning Calorimetry (DSC). Spinodal decomposition significantly changes the characteristics of the martensitic transition, reducing the transformed volume and modifying the critical temperatures. Furthermore, transformation hysteresis loop narrows as the volume fraction of the spinodal precipitates increases. Effects of thermal cycling through the martensitic transformation were studied in aged alloy samples. It was found that cycling produces critical temperatures changes, an increase in the transformed volume fraction, and a wider hysteresis loop. The observed results were discussed considering the interaction between spinodal precipitates and martensitic plates.