High-temperature oxidation behavior of high entropy carbide (TaNbTiV)C in atmospheres with different oxygen contents

A high entropy carbide (TaNbTiV)C was fabricated via spark plasma sintering of high entropy powders that were prepared using a molten salt method. The as-fabricated high entropy carbide was then investigated for its high-temperature oxidation behavior at 850 °C, under atmospheres with three different oxygen contents (20 vol%, 40 vol%, and 60 vol%). After the high-temperature oxidation process, the main phases observed in all the specimens were incompletely oxidized phase (Nb x Ti 1-x )C y O 2-y and oxides (Nb 0.5 Ta 0.5 ) 2 O 5 , TiO 2 , and Nb 2 O 5 . Importantly, the thickness of the oxide layer initially increased and then decreased as the oxygen content increased. When the oxygen content reached 40 vol%, the ceramic displayed severe oxidation behavior with observed thicker of the oxide layer, as well as numerous pores and cracks in the oxide layer. This work provides new insights into the oxidation behavior of high entropy carbides.