Influence of Titanium on the High Temperature Oxidation and Chromia Volatilization of Ternary Ni–Cr–C Alloys

International audienceTwo ternary alloys, Ni-25Cr-0.25C and Ni-25Cr-0.50C (wt.%) and three versions containing also titanium (1 and 2 wt.%) were cast and submitted to oxidation in dry synthetic air at 1200°C to observe the effects of titanium on the behaviors of the nickel-based alloys belonging to this category. The mass gains are wholly parabolic in all cases and the values of the parabolic and chromia-volatilization constants are typical of a chromia-forming behavior. The mass gains of the Ti-containing alloys are faster than for the Ni-Cr-C alloys, and these kinetic differences are consistent with the differences in chromia thickness and in Cr-impoverishment of the subsurface. In addition the presence of Ti led to the development of thin a TiO2 outer scale isolating chromia from hot air, but without benefit for the protection of Cr2O3 against volatilization. The obtained results also suggest that Ti may perturb the Cr diffusion in volume but also delay the oxide spallation during cooling