Microstructure and wear resistance of red mud iron alloy with chromium and titanium

Red mud is a solid waste in the production of alumina from bauxite. Red mud iron alloy (RMIA) is prepared from the red mud and laterite nickel ore via the high-temperature carbothermal reduction smelting and refining. Herein, by adjusting the contents of chromium (Cr) and titanium (Ti) in RMIA, low alloy cast iron with high hardness and wear resistance was obtained. Optical emission spectrometer, optical microscope, scanning electron microscopy, and hardness and two-body wear test were used for characterization. The results show that the addition of either Cr or Ti element can lead to carbide formation and refining of graphite. With an increase in the content of Cr or Ti, the hardness and the wear resistance of the alloy were enhanced, and the effect of Cr element was better than that of Ti element. The optimal microstructure and properties of the alloy were obtained at 4.8%Cr0.36%Ti, at which stage, the network eutectic carbide structure disappeared and evenly distributed in the matrix, and meanwhile, the graphite morphology was refined. The hardness of the alloy was higher than high chromium cast iron (HCCI), and the wear resistance of the modified alloy was better than HCCI under low load. The aim of this work is to provide a reference for the preparation of wear-resistant ferroalloys from the red mud directly via high-temperature carbothermal reduction.