Etude de l’impact des défauts (interfaces et/ou soluté) sur le comportement des intermétalliques par modélisation à l’échelle atomique

The initial goal of the thesis is to investigate the influence of defects on the behavior of TiAlbased alloys with a view to their integration in aircraft and automobile engines. Indeed, the addition of impurities can improve the hot behavior of these intermetallics. Their properties may also depend on the characteristics of interfaces, such as their atomic structure, adhesion, composition, and the nature of the interfacial bonds. Analysis of the fundamental properties of the gamma/alpha2 binary-phase interface of titanium aluminides in the presence of point defects provides access to these characteristics using the Density Functional Theory (DFT) within the generalized gradient approximation framework which is accurate for examining the behavior of these intermetallics, including their mechanical properties (cleavage energies), the geometry of the atomic structure, and their electronic structure (nature of the bonds). The results of this work show that the substitution and/or insertion of solutes remains an efficient solution to improve the mechanical behavior of TiAl-based alloys