Effect of microwave processing on the oxidation behavior of refractory high entropy alloy

Abstract

Abstract The effect of microwave processing on the high temperature oxidation behavior of AlCrTiTaMo equimolar composition was investigated. The long term oxidation studies were carried out at 900\xa0°C and 1100\xa0°C for 100\xa0h. Oxidation kinetics of the microwave-processed alloy yields a significant decrease in the oxidation rate and mass gain compared to the as-cast alloy. The physical nature and stability of thermally formed oxide on the as-cast and processed samples were probed using long-term electrochemical impedance spectroscopy (EIS) studies. The impedance of the oxide formed on the as-cast alloy decreased with the immersion time while it continuously increased for the microwave processed alloy suggesting its stable and defect free nature. The superior oxidation behavior of microwave-processed alloy was attributed to microstructural homogenization leading to the formation of protective oxide layer with favorable chemistry and structure.