Enhanced oxidation resistance of MoTaTiCrAl high entropy alloys by removal of Al

Refractory high-entropy alloys (HEAs) exhibit remarkable mechanical properties desired for high-temperature applications. However, their oxidation resistance at high temperatures received less attention. Recent work indicates that MoTaTiCrAl alloy exhibits excellent oxidation resistance, but the effects of Al and Cr remain unclear. In this work, we demonstrate that the addition of Al is unnecessary for preventing oxidation of the MoTaTiCrAl alloy and the removal of Al leads to a more oxidation resistant MoTaTiCr medium entropy alloy. Structural and chemical analyses indicate that the excellent oxidation resistance of MoTaTiCr is mainly associated with the formation of continuous CrTaO(4)oxide layer. The results indicate that complex oxides can be adopted as effective candidates for enhancement of oxidation resistance, in addition to typical strategy of forming Al2O3, Cr(2)O(3)or SiO(2)barrier layer.

Automated summary

Recent research shows that the excellent oxidation resistance of MoTaTiCr alloy is mainly associated with the formation of a continuous CrTaO(4) oxide layer, suggesting that complex oxides can be effective candidates for enhancing the oxidation resistance of high-entropy alloys.