A stepped habit plane between Widmanstätten cementite and austenite, related by a Pitsch or T¯H orientation relationship, was rationalized in terms of equilibrium interfacial structures. The secondary lattice misfit in the habit plane was completely accommodated by a set of secondary edge dislocations whose Burgers vector was inclined to the habit plane. Each dislocation core coincided with the riser of a step, whose terrace plane contained dense CCSL points. Although the Burgers vectors of the secondary dislocations were not determined experimentally, the calculated interfacial structures were consistent with the observed geometry of the linear defects and the extra planes associated with the steps. The condition for the orientation relationship to permit a coincidence structure was equivalent to a parallelism rule and indicated a direct link between the microscopic structure and the macroscopic description of the habit plane.

Coincidence Structures of Interfacial Steps and Secondary Misfit Dislocations in the Habit Plane between Widmanstätten Cementite and Austenite. F.Ye, W.Z.Zhang: Acta Materialia, 2002, 50[11], 2761-77