Synergistic effects of Al and Ti on the oxidation behaviour and mechanical properties of L12-strengthened FeCoCrNi high-entropy alloys

Abstract

Synergistic effects of Al and Ti on the oxidation behaviour and mechanical properties of FeCoCrNi high-entropy alloys were systematically investigated. Our results reveal that increasing the Al/Ti ratio slows down the oxidation kinetics at 700−900 °C and changes the oxide scale from TiO2 and spinel oxides to Cr2O3 and Al2O3, leading to a substantial improvement of oxidation resistance. From a mechanical aspect, however, increasing the Al/Ti ratio decreases the mechanical strength, demonstrating a strong trade-off between oxidation resistance and mechanical properties. The underlying mechanisms for the Al and Ti effects on the oxidation resistance and mechanical properties were discussed.