Transmission electron microscopy study of dislocation structures in iron-doped al₃ti with the l1₂ structure

Abstract

The dislocation structures and dissociation modes of superdislocations in L1₂-modified A1₆₇Fe₈Ti₂₅ deformed at room temperature and 600[ddot]C were investigated by means of transmission electron microscopy. It was revealed that in samples deformed at room temperature, dislocations dissociated into two (a/3)<112> superpartials separated by superlattice intrinsic stacking faults on {111} planes with a strong tendency to form dipoles. In samples deformed at 600[ddot]C, dislocations dissociated into two (a/2)<110> superpartials separated by antipnase boundaries on the cube {001} planes, predominantly with near-edge character. The factors controlling the plastic behaviour and brittleness of the L1₂-modified Al₃Ti at low and high temperatures are discussed in relation to the observed dissociation modes of superdislocations in this material.