Solid-State Processing Route, Mechanical Behaviour, and Oxidation Resistance of TiAl Alloys

Figure 12

Schematic model that illustrates the development of reflection spots dependent on the different processes that might occur during hot deformation of TiAl alloys. Starting with a perfect grain, plastic deformation increases from left to right. The development of the corresponding reflection spot is indicated below. In (a), a sharp reflection spot of a perfect grain is visible. Images (b) and (c) show how dislocations are introduced by plastic deformation which forms a subgrain boundary in (b) through dynamic recovery processes and eventually a high-angle grain boundary in (c). In contrast to this, images (d) and (e) show a case where the defect density increases until the onset of recrystallisation which is illustrated by the nucleation of new grains (adopted from [120]).