Microstructure and wear properties of nitrided AlCoCrFeNi high-entropy alloy

The nitrided layer was prepared on the AlCoCrFeNi high-entropy alloy by plasma nitriding. The microstructure and tribological property of the nitrided layer and as-cast high-entropy alloy were studied at dry sliding condition, deionized water and the acid rain, respectively. The results showed that the hardness of the nitrided high-entropy alloy was increased from HV 522 of as-cast high-entropy alloy to HV 720 of nitrided high-entropy alloy due to the presence of hard phases and solid-solution strengthening. In addition, the wear resistance of the nitride layer was superior to that of the as-cast alloy in the same condition. Moreover, the wear rate of nitride layer obtained a minimum of 2.8 × 10−5mm3/(Nm)in the acid rain due to the oxidation film, nitrided layer and the lubrication action in solution. The dominant wear mechanism of the as-cast alloys and the nitrided HEAs in the acid rain was abrasive wear, oxidative wear and corrosive wear. However, the main wear mechanism of the as-cast alloys and the nitrided HEAs in air and deionized water was abrasive wear, adhesive wear and oxidative wear. •Wear rate of nitrided HEAs was lower than that of as-cast HEAs in the same condition.•The wear mechanism of as-cast alloys in air was abrasive wear of oxide particles.•The wear mechanism of the nitrided HEAs in air was adhesive wear and abrasive wear.•The wear mechanism of HEAs in acid rain was abrasive, oxidative and corrosive wear.•The lubrication action of deionized water and acid rain led to the lower wear rate.