Nonthermoelastic and Thermoelastic Martensitic Transformation Behavior Characterized by Acoustic Emission in An Fe-Pt Alloy

Abstract

ABSTRACTAcoustic emission (AE) signals generated during the martensitic transformation in an Fe-24at%Pt alloy with various ordering treatments have been measured, and the AE parameters have been correlated with phase transformation events. AE events are generated during cooling of specimens, which is the first detection of the AE events associated with the martensitic transformation in Fe-Pt alloys. In all specimens, AE events were observed at higher temperature than the Ms temperatures determined by electrical resistivity measurement. AE events started to increase abruptly for the weakly ordered specimen with decreasing temperature. In contrast, AE events increased gradually for the highly ordered specimen with decreasing temperature. This is consistent with the nature of the transformation behavior in this alloy. The critical defect size of weakly ordered and highly ordered specimens were calculated using Ms temperature determined by AE technique. Results obtained in this investigation strongly suggests that the AE technique is useful for analysis of transformation kinetics in this alloy.