STRAIN-INDUCED MARTENSITIC-TRANSFORMATION IN A COPPER-IRON ALLOY - EXPERIMENTS AND MODELING

The influence of the mean size of austenitic Fe-precipitates in a copp er matrix on their stability against a strain-induced martensitic tran sformation is studied. For this purpose rolling experiments are conduc ted using specimens containing differently sized particles. The progre ss of the transformation is monitored by measuring the magnetic suscep tibility of the material as a function of the plastic strain. It follo ws an Avrami-type function. The stability of the precipitates increase s with decreasing particle size. The predictions of a continuum mechan ical model based on a thermodynamical concept agree with the experimen tal findings. The model makes possible the calculation of a size-depen dent mechanical driving force and allows to study various transformati on mechanisms.