Weak-beam study of dislocations in D022-Al3Ti deformed at 400°C
Résumé
Polycrystalline samples of Al3Ti with the D022-type structure have been plastically deformed at 400°C. Observations using weak-beam transmission electron microscopy show activation of dislocations with <100] or <110] Burgers vectors. The fine structure of [100] and [010] dislocations reveals strong stabilization effect on the pure edge character. [110] superdislocations, resulting from the interactions between [100] and [010] perfect dislocations, are dissociated in two identical superpartials separated by an antiphase boundary (APB). Their segmented shape together with the separation distances between the [110] superpartials point to a large anisotropy of APB energies whose estimated values on (001) and (111) are 13 ± 3 mJ/m2 and 64 ± 5 mJ/m2, respectively. The low mobility of <100] and <110] dislocations is highlighted and related to the low ductility of this material. © 2013 Copyright Taylor and Francis Group, LLC.