On the relation between orientation relationships predicted by the phenomenological theory and internal twins in plate martensite

The phenomenological theory of martensite crystallography predicts two equivalent solutions for a particular habit plane in the case of a Fe-Ni-C alloy. Those two solutions differ in the magnitude of the inhomogeneous shear and in the orientation relationship (OR) they hold with austenite. Only the OR associated to the low shear solution has been observed experimentally so far. In the present study, the orientation relationship associated to the high shear solution is assessed experimentally using TEM measurements.