  Analytical treatments, formulated to predict the rate of the bainite
transformation, define autocatalysis as the growth of the subunits at the
bainite-austenite interface. Furthermore, the role of the stress-free
transformation strain is often translated to a thermodynamic criterion that
needs to be fulfilled for the growth of the subunits. In the present work, an
elastic phase-field model, which elegantly recovers the sharp-interface
relations, is employed to comprehensively explicate the effect of the elastic
energy on the evolution of the subunits. The primary finding of the current
analysis is that the role of eigenstrains in the bainite transformation is
apparently complicated to be directly quantified as the thermodynamic
constraint. It is realized that the inhomogeneous stress state, induced by the
growth of the primary subunit, renders a spatially dependent ill- and
well-favored condition for the growth of the secondary subunits. A favorability
contour, which encloses the sections that facilitate the elastically preferred
growth, is postulated based on the elastic interaction. Through the numerical
analyses, the enhanced growth of the subunits within the favorability-contour
is verified. Current investigations show that the morphology and size of the
elastically preferred region respectively changes and increases with the
progressive growth of the subunits.

Materials Science