Habit planes of climbing and gliding dislocations in TiAl determined in three dimensions by electron tomography

Abstract

In this study, the habit planes of dislocations moving by glide and climb at 850–900 °C have been determined in three dimensions (3D) by electron tomography, using the TiAl intermetallics as a model system. An almost complete digital 3D reconstruction approach has been implemented, based on algorithms developed in life sciences, with which the habit planes orientations have been obtained with ±5° accuracy. It could thus be demonstrated, notably, that climbing a[001] pure edge dislocations loops, previously identified in literature, actually constitute Bardeen-Herring sources. Moreover, mixed-climb in {011) planes has been properly evidenced, as well as coexistence of gliding and climbing dislocation segments in the same region of the crystal. Consequently, improving the material's strength at 850–900 °C would require controlling both the glide and climb mechanisms by means of suitable solutes.