Defect modelling of martensitic interfaces in plate martensite

A physical model of martensitic transformations describing the structure of the parent-martensite interface and the transformation mechanism is presented. This approach is used here to model martensitic transformations in lath and plate martensite. The habit plane comprises coherent (1 1 1)γ//(0 1 1)α terraces where the coherency strains are accommodated by a network of near screw dislocations, originating in the martensite phase, and disconnections (transformation dislocations), also in near screw orientation. The lateral motions of the disconnections effecting the transformation shear; moreover, the transformation process is explicitly shown to be diffusionless. Experimental observations from the literature of the dislocation and disconnection arrays, habit plane and orientation relationship are in good agreement with the model.