Determination of the Orientation of a Parent β Grain from the Orientations of the Inherited α Plates in the Phase Transformation from Body-Centred Cubic to Hexagonal Close Packed

Knowledge of the orientations of several α plates inherited from the body-centred-cubic–hexagonal-close-packed phase transformation of a β grain allows us to determine the orientation of the latter, provided that a strict orientation relation between the two lattices exists. This contribution discusses the problem of the uniqueness of the solution and leads to the conclusion that the number of different α orientations required for that purpose is three in the less favourable case but is reduced to two in the most favourable case.