The influence of Nb diffusion on the oxidation behavior of TiNiAlNb alloys with different Ti/Ni ratio

The oxidation behavior of TiNiAlNb with different Ti/Ni ratio was investigated. The diffusion of Nb during the oxidation was studied by EPMA analysis of the composition in different oxide layers and the sub-surfaces. The diffusion behavior of Nb either entering into the outer TiO2 or forming Nb-rich oxide layer beneath outer TiO2 are related to the Ti/Ni ratio of the alloys. The different diffusion behaviors of Nb also have effects on the oxidation kinetics of TiNiAlNb alloys. The study shows that Nb doping in TiO2 is more effective in improving the oxidation resistance of TiNiAlNb alloys.