Abstract
All the first order phase transformations proceed through the nucleation and growth process. The martensitic transformation is characterized by the synchronized motion of a group of atoms. The problem of the nucleation of the martensite is to find a nucleation mechanism compatible with the synchronized and finite displacement of a group of atoms, which consists of the synchronized dislocation slips of neighboring slip planes. The synchronized dislocation slip is discussed in terms of two models: the modified version of the nucleation model and the one-dimensional large amplitude lattice vibration model. The negative surface energy for the coherent interface is introduced to the nucleation and growth model in order to take into account that the elementary microscopic process in the martensitic transformation is the synchronized motion of atoms in a slip plane. The major theories proposed for the martensitic transformation, the classical nucleation theory, the local soft mode theory and the dislocation theory, are briefly discussed from the viewpoint presented above.
