POSSIBLE MECHANISM HETEROGENEOUS LAYERED STRUCTURES FORMATION DURING GROWTH OF MARTENSITE CRYSTALS

Abstract

The main features of iron-based g-a MTs are briefly described, including macroscopic morphological features and supersonic (relative to longitudinal waves) crystal growth rate. The key provisions of the dynamic theory of martensitic transformations are listed. It is noted that the idea of a quasi-equilibrium nucleus in the dynamic theory is replaced by the concept of an initial excited state arising in the elastic field of a dislocation nucleation center and generating a wave process that controls the formation of martensitic crystal growth. It is essential that the controlling wave process inherits and transfers the deformation created in the region of localization of the initial excited state. It is shown, using the example of crystals of surface martensite with habits close to {112}, that the growth of crystal faces within the framework of the dynamic theory can be interpreted as the formation of thin layers parallel to the faces, and the resulting layers can directly contact the faces of the original crystal, or be separated by layers representing distorted residual austenite or martensite, generally distinguished by the choice of the main axis of Bain deformation and, probably, orientation relationships. Thus, inhomogeneous structures can be observed in the peripheral regions of martensite crystals. Clarification of the specifics of such inhomogeneities requires separate studies.