The mechanical properties and high-temperature oxidation behavior of (TiZr)_65-x-yNb₁₅Mo₂₀Si_xAl_y refractory high entropy alloys

Herein, the mechanical properties and high-temperature oxidation of (TiZr)_65-x-yNb₁₅Mo₂₀Si_xAl_y refractory high-entropy alloys were systematically investigated. Results indicate that alloying with Si improves the strength but reduces the plasticity of the alloy. Maintaining a proper ratio of Al/Si is crucial to achieve the optimal performance of the alloy. The (TiZr)_50.5Nb₁₅Mo₂₀Si_9.5Al₅ has excellent high-temperature performance, with a yield strength of 815 MPa at 800°C and a compressive strain greater than 40 %. Moreover, the (TiZr)_50.5Nb₁₅Mo₂₀Si_9.5Al₅ exhibits a superior oxidation resistance compared to (TiZr)₅₅Nb₁₅Mo₂₀Si₁₀ alloy at 1000℃. The introduction of Si enhances the oxidation resistance, decreases the diffusion of the Zr element at 1000 °C and facilitates internal oxidation and the creation of TiNb₂O₇. However, it is important to note that the doping of Al in the higher Si alloys has negative impacts on the oxidation resistance and mechanical properties.