Significantly Enhanced Wear Resistance of an Ultrafine-Grained CrFeNi Medium-Entropy Alloy at Elevated Temperatures

The hardness and pin-on-disk sliding wear behavior of CrFeNi medium-entropy alloy (MEA) against Inconel alloy 718 at room and elevated temperatures were investigated. The results show that the hardness and coefficient of friction of CrFeNi MEA linearly decrease with elevating temperature. The wear rates at 300 degrees C and 600 degrees C are 40- and 150-times lower than that at room temperature (25 +/- 1 degrees C), respectively. The wear rate of CrFeNi MEA at 600 degrees C is only similar to 25 pct of that of Inconel alloy 718. Surface microstructure evolution and wear mechanism were discussed in detail. The significantly enhanced wear resistance at elevated temperatures is mainly attributed to the formation of the glaze layer which consists of a dense equiaxed nanocrystalline oxide layer and a mechanically mixed layer of nanocrystalline oxides and partially oxidized pin and disk alloys.