Oxidation behavior of Ti-Nb-Mo-Al-Si_x refractory high entropy alloy at 1000℃

The oxidation behavior of TiNbMo_0.5Al_0.225Si_x (x = 0.1, 0.25, 0.4, 0.55) refractory high entropy alloys in air at 1000 ℃ was investigated. These novel alloys have a BCCss / (Nb, Ti)₅Si₃ eutectic structure in the as-cast state. Oxidation resistance results reveal that the mass gain shifts from a mass loss (Si_0.1) to a parabolic law (Si_0.25, Si_0.4, Si_0.55). An appropriate increase in Si content favors a lower oxidation rate. The β-(Nb, Ti)₅Si₃ was studied to have excellent oxidation resistance, while the region where γ-(Nb, Ti)₅Si₃ existed is the main site of porosity generation. The suitable Si content promotes the appearance of a Mo-rich layer, thus preventing the oxide evaporation. Data availability: The data that support the findings of this study are available from the corresponding author, specifically Professor Liang Wang of the Harbin Institute of Technology (email: wliang1227@hit.edu.cn) upon reasonable request.