Comparison between the invariant line and structural ledge theories for predicting the habit plane, orientation relationship and interphase boundary structure of plate-shaped precipitates

A comparison is made between the invariant line and structural ledge theories for predicting the habit plane, orientation relationship and (misfit) dislocation structure at interphase boundaries for various transformation strains. It is shown that the fundamental approaches of the invariant line and structural ledge theories are significantly different and that this can lead to the same or different predictions for the habit plane, orientation relationship and dislocation structure between two crystals depending on the type of transformation strain. It is also shown that the structural ledge theory is not applicable to transformations that involve expansion or contraction between orthogonal lattices. © 1992.