Investigation on oxidation behavior and mechanical properties of FeCoNiNbAlCrTa high entropy alloy at 900 ° C

In recent years, eutectic high entropy alloys have been found to have excellent mechanical properties and corrosion resistance; however, the simultaneous achievement of these mechanical properties and high- temperature oxidation resistance still constitutes a tough challenge. In this study, Ta and Cr elements are added to (FeCoNiNb)98Al2 high-entropy alloy to improve oxidation resistance, and the changes in microstructure and mechanical properties of (FeCoNiNb)98-2x(TaCr)xAl2 as well as the oxidation behaviors at 900 degrees C are systematically investigated. The results show that the addition of Ta and Cr elements promotes the increase and growth of the Laves phase in the alloy, which improves the oxidation resistance of the alloy and maintains the excellent mechanical properties of (FeCoNiNb)98Al2. The formation of CrTaO4, CrNbO4, and Cr2O3 composite oxide scales can not only prevent the diffusion of O into the alloy, but also inhibit the external diffusion of matrix elements. This result provide experimental data and theoretical support for the optimal design of the high- entropy alloy compositions to improve their antioxidant properties while maintaining excellent mechanical properties.