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

The oxidation behavior of TiNbMo 0.5 Al 0.225 Si 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) 5 Si 3 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) 5 Si 3 was studied to have excellent oxidation resistance, while the region where γ-(Nb, Ti) 5 Si 3 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. 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. • Doping the Si into the TiNbMo 0.5 Al 0.225 RHEA effectively reduces oxidation rate and improves oxidation resistance. • The β-(Nb, Ti) 5 Si 3 exhibits better oxidation resistance than γ-(Nb, Ti) 5 Si 3 . • A Mo-rich layer is formed with the increasing Si concentration, thus inhibiting the evaporation of MoO 3 .