CRYSTALLOGRAPHY OF BCC TO ORTHORHOMBIC GAMMA1' MARTENSITE TRANSFORMATION IN COPPER-TIN ALLOYS

The habit plane, shape strain and orientation relationships associated with the formation of orthorhombic γ1′ martensite plates in Cu-14.95 at.% Sn alloys have been measured. The results are compared with the predictions of the phenomenological theory of martensitic transformations first by assuming the complementary strain to be a shear on the martensite twinning system, and secondly by using the measured habit plane to derive a complementary strain, orientation relationship and displacement direction. The results indicate that the complementary strain does not appear to be a simple shear. © 1969.