TRANSMISSION ELECTRON-MICROSCOPY STUDY OF DISLOCATION-STRUCTURES IN IRON-DOPED AL3TI WITH THE L1(2) STRUCTURE

The dislocation structures and dissociation modes of superdislocations in L1(2)-modified Al67Fe8Ti25 deformed at room temperature and 600-degrees-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-degrees-C, dislocations dissociated into two (a/2)<110> superpartials separated by antiphase boundaries on the cube {001} planes, predominantly with near-edge character. The factors controlling the plastic behaviour and brittleness of the L1(2)-modified Al3Ti at low and high temperatures are discussed in relation to the observed dissociation modes of superdislocations in this material.