Martensitic transformation in Cu-11.39 wt pct Al-5.8 wt pct Mn alloy has been studied using acoustic emission(A.E.) and electric resistance measurements.
$A_s$ and $M_f$ temperatures and the width of total electric resistance change decreased as the number of cycle increased. The results are explained in terms of remained austenite phase. The change of elctric resistance was compared with the model of serial and parallel connections of two phases during transformation. The amount of ringdown count varied with the direction of transformation and number of thermal cycle. The dependence of the ringdown count on the thermal cycle are explained in terms of effective volume available during martensitic transformation.
Peak amplitude distribution showed that large amplitude of A.E. generated as the number of the thermal cycle increased and is related to the events duration and rise time of A.E. event. It is suggested that the temperature dependence of A.E. peak on the cooling or heating rate is governed by A.E. mechanisms; martensite formation during cooling, and austenite formation and martensite annihilation during heating.
