Learning through cycling in martensitic phase transitions

The effect of thermal cycling in the martensitic phase transitions of a Cu–Zn–Al single crystal shape-memory alloy has been studied by monitoring the acoustic activity generated during the transition. The correlation function between the acoustic activity of k   and k+Δk cycles has been computed for the whole transformation and for selected temperature intervals ΔT within the transition region. Results indicate that for the whole transition there is a learning process in which the system seeks an optimal path of its internal variables that connect the parent and the martensitic phases. The learning process in the central part of the transition dominates the global behaviour and is different from the behaviour in the early- and late-stages of the transition.