Effect of nitriding on the tribological properties of Al1.3CoCuFeNi2 high-entropy alloy

The nitrided layer on Al1.3CoCuFeNi2 high-entropy alloys (HEAs) was prepared by plasma nitriding. The hardness, microstructure, tribological properties and adhesive strength of nitrided layer were studied. The microstructure and tribological property of the nitrided layer and as-cast HEAs were investigated under the dry sliding condition, deionized water and acid rain. The results showed that the as-cast Al1.3CoCuFeNi2 HEAs contained both simple FCC and BCC solid solution phase. After nitriding, AlN and Fe4N were phases formed on the surface of the nitrided alloys. Besides, the hardness of the nitrided alloy was increased from HV 340 of as-cast HEAs to HV 587 of nitrided one. The deionized water and acid rain acted as lubricant and cooling liquid to some extent. Simultaneously, the acid rain also acted as corrosive. The wear mechanisms of the as-cast alloys and the nitrided HEAs in air and acid rain were mainly abrasive wear accompanied by oxidative wear as well as adhesive wear. In compasion, the main wear mechanisms in the as-cast alloys and the nitrided HEAs in the acid rain were corrosive and abrasive wears.