Effects of Al/Si on the oxidation behavior of a TiZrV0.5Nb0.5 refractory high entropy alloy at 1000 ℃

For the TiZrV0.5Nb0.5 RHEA as a model material, different mechanisms of Al and Si inhibiting its inherent catastrophic oxidation were systematically elucidated by analyzing the cross-section oxide layer and performing the XPS line scanning technology. Al/Si-alloying enhances oxidation resistance via improving the anti-spallation of oxide layer. A niobium oxide protective layer occurred on Si-containing alloy, accompanied by a pinning-effect of second-phase oxides and inhibition of oxide volatilization. Improvement oxidation resistance of TiZrV0.5Nb0.5Al0.75 arises from a significant reduction in the oxygen inward diffusion and subsequent inhibition of oxide volatilization caused by the rapid diffusion and preferential oxidation of Al.