Micromechanical modeling of γ-TiAl [gamma-TiAl] based alloys

Based on the identified key issues in the process of ?-TiAl based alloy development, three main research objectives were addressed in this thesis: First, an EBSD based method should be developed for the identification of ?-TiAl order domains. The progress in the available instrumentation and software for data acquisition and data interpretation brought this delicate task into reach. Second, based on preexisting knowledge on single crystal indentation and cryst plasticity constitutive modeling, a method should be developed to characteriz the single phase deformation behavior of stoichiometric ?-TiAl in a quantitativ fashion. Third, a constitutive model should be developed that can take into account the current understanding of the kinematic constraints that are imposed by the crystallographic and phase interfaces in two-phase ?/a2 microstructures. For the micromechanical modeling work, emphasis was laid on quantitative validation of the developed modeling approaches against experimental data. Therefore, a restriction to the investigation of the room temperature micromechanics was imposed. In this way, the corresponding experimental work could be carried out in parallel to the modeling. Furthermore, the room temperature mechanical behavior of titanium aluminides is of interest from the viewpoint of fundamental research as well as through the issue of limited ductility of ?-TiAl based alloys at ambient and intermediate temperatures.