Static and cyclic oxidation of Nb-Cr-V-W-Ta high entropy alloy in air from 600 to 1400 °C

Abstract

An oxidation resistance study has been made on Nb-Cr-V-W-Ta high entropy alloy in a range of temperature from 600 to 1400 °C in air. Static oxidation study has been performed for either (a) 12 or 24 h of heating time or (b) 3 or 10 °C/min heating rates to the desired oxidation temperature. Cyclic oxidation study conducted for three and a half days has been conducted at 600, 700, and 800 °C using 12 h of heating cycles. The alloy can withstand the cyclic oxidation process with only a reasonable loss of alloy. The identification of oxides indicates crystals of W and Ta oxides in cylindrical form while Nb and Cr oxides show a nodular or granular morphology at both 1000 and 1200 °C while and additional of oxide of V in whisker forms at 1200 °C.