A MODEL OF THE FREE-ENERGY FOR MATERIALS WHICH UNDERGO MARTENSITIC PHASE-TRANSFORMATIONS WITH SHUFFLES

A three-dimensional model of the free energy for materials which under go martensitic phase transformations with shuffles is suggested. The f orm of the free energy is considered the point of view of the distribu tion of basal planes, habit planes and symmetries of austenitic and ma rtensitic structures. The shuffles are considered as a micro-nonhomoge neous deformation. This deformation is described by means of the relat ive displacement vectors. The internal rotations of the martensite tow ards habit planes are discussed. To this end a variable connected with a material director is introduced. The flat character of the propagat ing interfaces is described by means of higher gradients of deformatio n. The form of the free energy suggested in the paper leads to a mecha nical classification of the martensite variants.