In-situ diffraction study of the positive impact of nitrogen on the high temperature oxidation of Ti alloys

Titanium alloys use at high temperature is limited by the oxide scale growth and by the O dissolution in the alloy. Nitrogen contained in the atmosphere may play an important role on the oxidation resistance, as it reduces the kinetics by accumulating at metal/oxide interface. The mechanisms leading to positive impact of nitrogen are still not yet understood, as N-rich phases that may form crystallize with the same crystallographic structure and have very close lattice parameters to O-rich phases. High (hkl) diffraction peaks are needed in order to differentiate between these phases, but they are not accesible with laboratory X-ray wavelenghts.The aim of the in-situ synchrotron experiment is to investigate N-rich phases forming in ambient air at high temperature. Their growth will be followed during the first exposure stages and the time when they form will be identified with respect to O-phases. The impact of alloying elements will be studied by using different composition Ti alloys.