Effect of Ti and C addition on oxidation resistance of FeCoCrNiMn high entropy alloys prepared by powder metallurgy

Purpose The purpose of this paper is to study the high temperature oxidation behavior of Ti and C-added FeCoCrNiMn high entropy alloys (HEAs). Design/methodology/approach Cyclic oxidation method was used to obtain the oxidation kinetic profile and oxidation rate. The microstructures of the surface and cross section of the samples after oxidation were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Findings The results show that the microstructure of the alloy mainly consisted of FCC (Face-centered Cubic Structure) main phase and carbides (M 7 C 3 , M 23 C 6 and TiC). With the increase of Ti and C content, the microhardness, strength and oxidation resistance of the alloy were effectively improved. After oxidation at a constant temperature of 800 °C for 100 h, the preferential oxidation of chromium in the chromium carbide determined the early formation of dense chromium oxide layers compared to the HEAs substrate, resulting in the optimal oxidation resistance of the TC30 alloy. Originality/value More precipitated CrC can preferentially oxidize and rapidly form a dense Cr 2 O 3 layer early in the oxidation, which will slow down the further oxidation of the alloy.