RELATION BETWEEN DISPLACIVE DISORDER, PREMARTENSITIC INSTABILITIES AND THE MARTENSITE FORMATION IN beta -Cu-Zn ALLOYS - 3. GEOMETRICAL AND PHYSICAL MODEL FOR MARTENSITE FORMATION.

Using a lattice matching theory based on zonal dislocations which was proposed by S. Mendelson, the crystallography of the bcc beta phase to 9R or 2H martensite transformation in copper zinc alloys was analyzed. The model used, which consists of a combination of shuffle mechanisms with or without additional shear, takes into account the premartensitic atomic movements as well as the measured and observed crystal structures, orientations, and habit planes.