Generalized Ginzburg-Landau functional calculations of the structure and energy of the coherent interphase boundaries between austenite and martensite in iron

Abstract

The earlier-developed methods and experimental data on the phonon spectra and thermodynamics of fcc and bcc iron are used to construct a generalized Ginzburg-Landau functional for microscopic investigations of the austenite-martensite phase transformations in iron. This functional is used to calculate the structure and properties of a plane austenite-martensite interface for arbitrary orientations of this interface at various temperatures. The transformation parameter profiles in the interface region are calculated. The interface width is found to substantially exceed the interatomic distances. The interfacial surface energy is 500–800 erg/cm2, depends strongly on the orientation, and has a sharp maximum when the interface is parallel to a close-packed plane.