Study on microstructure and oxidation behavior of Fe–xMn–14Al–8Ni–C alloy prepared by vacuum arc melting

Abstract

In this study, Fe–xMn–14Al–8Ni–C alloy (x = 10, 15, 20, 25 wt.%) was prepared by vacuum arc melting method. The microstructure of this series of alloys and the oxidation behavior at 600 °C were studied. The conclusions are as follows: Fe–xMn–14Al–8Ni–C alloy mainly contains austenite phase, NiAl intermetallic compound phase and k-carbide phase. As the content of Mn increases, the amount of austenite increases while the amount of NiAl compound decreases. At the same time, the content of k-carbide phase precipitated at the interface between austenite and NiAl compound and inside austenite increases. The oxidation resistance results show that as the Mn content increases, the oxidation resistance of the alloy is improved. After oxidation, due to the difference in thermal stress and thermal expansion coefficient, the oxide film is mainly divided into two layers (when the Mn content is 10% and 15%, respectively), the outer oxides are Fe2O3 and a small amount of Mn2O3, the inner oxides are mainly the mixture of Al2O3, Mn2O3 and NiO. When the Mn content increases to 20%, the oxide film is a three-layer, and a uniform dense oxide film mainly composed of Al2O3 appears at the junction with the substrate, which better prevents the further diffusion of oxygen in the air to the inside and protects the substrate. The surface oxide film is dense and stable, so it can prevent further oxidation. Therefore, the alloy with 25% Mn content exhibits the most excellent oxidation resistance.