A Study of High and Low Angle Boundaries in Ti³Al

Abstract

High and low angle boundaries have been examined in Ti₃Al using atransmission electron microscope. The misorientations between thegrains were measured accurately and dislocation arrays were imagedwithin these boundaries. An analysis of the low angle boundarydemonstrates that its structure consists of an array of dislocationswith Burgers vectors equal to crystal translation vectors. This arrayaccommodates the angular deviation from the perfect crystallinestructure. The high angle boundary imaged in this specimen alsodisplayed dislocation contrast and the misorientation between thegrains was measured. However, reference structures accommodating thecorresponding deviation could not be unambiguously identified in theobserved dislocation array. The problems of relating the dislocationstructure in hexagonal materials to misorientation relationships arediscussed.