Microstructure stability and oxidation behaviour of (FeCoNiMo) ₉₀ (Al/Cr) ₁₀ high-entropy alloys

Abstract

Simple ordered L1 2 phase and complex ordered µ phase were found in the (FeCoNiMo) 90 Al 10 alloy, while disordered FCC and µ phases were detected in the (FeCoNiMo) 90 Cr 10 alloy. After annealing at 900°C, nano-size precipitates were observed in the L1 2 phase, and splitting and spheroidisation were occurred in some regions of the eutectic structures in the (FeCoNiMo) 90 Cr 10 alloy. After holding for 100 h at 900°C, (FeCoNiMo) 90 Al 10 alloy showed an excellent hardness resistance. The oxidation kinetics of both (FeCoNiMo) 90 Al 10 and (FeCoNiMo) 90 Cr 10 alloys followed a parabolic rate law at 900°C. An external layer of Al 2 O 3 and an underlying MoO 2 subscale were found in the (FeCoNiMo) 90 Al 10 alloy. A semi-continuous oxide layer of MoO 2 and Cr 2 O 3 was observed in the (FeCoNiMo) 90 Cr 10 alloy.