The aim of the project is development of new advanced cast multiphase gamma based TiAl-8Nb-X alloys alloyed with the graded carbon content (0.2 to 1 at. %), produced so far only by powder metallurgy. Sufficient thermo-mechanical stability of these alloys will be guaranteed by the lamellar structure strengthened by favorable distributed precipitates obtained using an optimized complex heat treatment. The main pertinent applications of the alloys suggested are turbocharger rotor or gas turbine blade in automotive and power industry, respectively, in which a decisive degradation mechanism represents creep-fatigue interaction at higher temperatures. The structure of new-developed cast alloys and its thermo-mechanical stability will be studied both in virgin state after optimized heat treatment and after high temperature creep-fatigue tests. Neutron diffraction (in-situ and post-mortem studies), TEM (transmission electron microscopy) and other modern experimental techniques will be used for the structure analysis and the study of damage mechanisms.