High-temperature oxidation behavior of a light-weight multi-component Nb-Ti-Al based alloy at 1000–1200 ℃

Nb-Ti-Al based alloys are one of the important lightweight high-temperature structural candidate materials for future aerospace components. However, the high-temperature oxidation behavior of multi-component Nb-Ti-Al-V-Zr-Hf-Mo alloy has not yet been fully elucidated, particularly regarding its oxidation behavior across different temperatures. Therefore, this work systematically investigated the isothermal oxidation behavior and mechanism of the Nb-Ti-Al based alloy at 1000, 1100, and 1200 ℃. The oxidation kinetics of the alloy followed an approximately linear rate law at 1000 ℃, whereas the behavior at 1100 and 1200 ℃ was better described by a parabolic law. The oxidation products formed during high-temperature oxidation of the alloy within the 1000–1200 ℃ range primarily consisted of TiO₂, Nb₂O₅, and TiNb₂O₇. Increasing the temperature facilitated the acceleration of the reaction between TiO₂ and Nb₂O₅ to form TiNb₂O₇, thereby promoting the rapid formation of a relatively dense oxide scale in the early oxidation stage. Notably, the stratification of the oxide scale becomes more pronounced with rising oxidation temperature, particularly at 1200 ℃, where the stratified structure is more distinct. The formation of such a stratified oxide scale is primarily related to the diffusion and enrichment of metal elements such as Ti and Al during high-temperature oxidation process. The dark region in the stratified area is mainly composed of TiO₂ and Al₂O₃.