Intersections of deformation twins in TiAl II. Models and analyses

Abstract

Abstract In TiAl with the L10-ordered structure there are two basic crystallographic configurations in which twin bands from two systems intersect each other, both of which have been investigated in this work. Transmission electron microscope observations described in part I have shown the structural changes associated with twin intersections in these two configurations. The aim of the present paper is to examine mechanisms in which the shear imposed by the incident twin on the barrier twin is accommodated. It is shown that in L10 many crystallographic relations exist in which the displacement continuity at the matrix/twin interface is maintained in shear transmissions. Most of them, however, are found to be inconsistent with the experimental observations. The present paper aims to investigate factors that have limited the occurrence of certain reaction schemes. It is found that the energetics measured in terms of the balance in the self energies of the dislocations involved is not sufficient to acount fo...