ON THE THERMODYNAMICS OF MARTENSITE NUCLEATION

Estimations of nucleation barriers for single-domain and multiple-domain states of a martensite phase have been obtained. A macroscopic approach, considering the free energy of a heterophase system to be a sum of the energy of the elastically stressed equilibrium phases and the energy of interfaces, was used. It has been shown that for the martensitic transformation in steels and iron alloys the nucleation of single-domain (single-crystal) martensite is impossible. The nucleation barrier for multiple-domain (twinned) martensite has been found to be of 103 times less than former estimations that had rejected any possibility of the homogeneous nucleation of martensite. © 1990.