”Optimisation” of imaging conditions for weak beam studies of dislocation core structures in Ti3Al

The imaging conditions for weak beam (WB) studies of dislocations in Ti3AI with intermediate voltage transmission electron microscopes have been derived following a theoretical examination of the traditional criteria for WB-microscopy. The cores of <2c+a>-dislocations in room temperature deformed Ti3AI have been characterised in a case study with 300kV electrons by experimental WB-microscopy, which used imaging conditions not satisfying the traditional WB criteria. Image simulations facilitated the determination of the corrected dislocation dissociation widths for dissociated edge character dislocations. A superpartial separation of 19.5nm has been determined from experimentally observed image peak separations of (2lf 1)nm for the edge dislocation cores.