Iron aluminides – A step towards sustainable high-temperature wear resistant materials

Iron aluminides are promising candidates for high-temperature corrosion- and wear resistant materials. Their intermetallic nature provides good mechanical stability at comparatively low density in contrast to commonly used iron- and nickel-based wear resistant alloys such as white cast irons or Inconel alloys. The objective of this study is to measure the influence of different alloy compositions on the high-temperature abrasion resistance of iron aluminides. Alloys of 25–30 wt% Al, Ti, B and Si were characterized and compared to a high-temperature resistant white cast iron. Microstructural analysis via scanning electron microscopy as well as electron backscatter diffraction were performed to elucidate the materials' microstructures and the different phases present. Hot hardness up to 700 °C and nanoindentation were determined to quantify differences in mechanical properties between compositions. Wear resistance was quantified with high-temperature abrasion tests performed in a modified ASTM G65 test at 20, 500 and 700 °C, with standard quartz sand as abrasive and a high-temperature resistant steel wheel as counterbody. Wear results point out a significantly better behaviour of the iron aluminides at 500 °C and 700 °C at a quarter of the wear rates of the white cast iron, which can be attributed to beneficial mechanical properties enabling the formation of protective mechanically mixed layer under incorporation of abrasives. Finally, a life cycle assessment (LCA) was performed to assess the environmental impact of the iron aluminides compared to the steel reference during production, accounting for the lifetime as indicated by the wear rates obtained. Results show significantly reduced environmental impacts in the evaluated impact categories, making iron aluminides promising candidates for future high-temperature wear components.