Design and development of Cr-Si based Intermetallic alloys

The motivation for the research described in this thesis was to study the oxidation behaviour of Cr rich Al and Si containing alloys with low transition metal additions as potential bond coat alloys for a coating system for ultra-high refractory metal silicide based alloys. The thesis is an experimental study of the microstructures of cast and heat-treated ternary Cr-Si-Al-M alloys with different Al/Si ratios and individual additions of up to 10 at.% M = Hf, Nb and Ti and of the isothermal oxidation of the cast alloys at 800, 1000 and 1200 oC. A brief review of relevant literature is given. The experimental techniques used in the research, namely DSC, X-ray diffraction (Bragg–Brentano and glancing angle), EBSD, TG, SEM and EDS are described. The isothermal heat treatment of the alloys was carried out under argon at 1200 and 1300 oC for 100 hours.