Dynamic Theory of Surface Martensite Formation, Allowing also a General Scenario of Lateral Growth

Building on Klostermann’s foundational work, we review surface martensite formation during γ-α transformation in electrolytically polished Fe-30% Ni alloys. It is noted, according to Klostermann, that the phenomenological approach of WLR is inapplicable to the interpretation of observed morphological features. The basic concepts of the dynamic theory of martensitic transformations are presented, in which the formation of a martensite crystal is associated with the propagation of a control wave process (CWP). Long-wavelength (l) components in the composition of the CWP determine the orientation of the habit plane, and the fine structure of transformation twins is dictated mainly by relatively short-wavelength (s) components. The inhomogeneous elastic field of the dislocation loop framing the habit plane is analyzed. Two options for the formation of crystalline layers that have the same (or with a close, almost parallel orientation) habit plane as the original crystal are discussed. If the layers are separated by layers of retained austenite, then it is appropriate to talk about the appearance of a stack of crystals. In the absence of interlayers, it is natural to use the term “lateral crystal growth”.