Dual effects of Cr doping on the high-temperature oxidation behavior of Mo2FeB2-based cermets

The effects of Cr doping on the high-temperature oxidation behavior of Mo 2 FeB 2 -based cermets were systematically investigated at 700 °C, 740 °C and 800 °C, respectively. The results indicated that the doped Cr element made dual effects on the oxidation behavior based on the varied oxidation temperatures, oxidation durations and Cr contents. At 700 °C and 740 °C, the oxidation resistance of Mo 2 FeB 2 -based cermets was enhanced by Cr doping less than 6 wt%, while the higher Cr content (8 wt%) reversely accelerated the oxidation rate. The positive effect was mainly derived from the formation of Cr-rich inner layer. As the oxidation temperature reached 800 °C, the superior oxidation resistance could be obtained in the first 20 h with Cr contents of 2 wt% and 4 wt% However, the longer oxidation durations or higher Cr contents could result in the swelling and cracking of oxide layer, then triggered the destructive oxidation. • The effects of Cr doping on the oxidation behavior and mechanism of Mo 2 FeB 2 -based cermets were studied. • The doped Cr mainly dissolved in Fe-based binder and enhanced the oxidation resistance of the binder. • The formation of Cr-rich inner layer exerted the positive effect on the oxidation resistance of Mo 2 FeB 2 -based cermets. • The excessive Cr contents accelerated the oxidation rate of Mo 2 FeB 2 -based cermets.