Microstructure and sliding wear behavior of FeCoNiCr0.8Al0.2 high-entropy alloy for different durations

In this study, FeCoNiCr0.8Al0.2 high-entropy alloy was fabricated by vacuum arc melting, followed by aging treatment for different durations. And the phase structure, microstructure, mechanical properties, and tribological behavior of the alloys were systematically studied. The results show that all the HEAs in this work have good structural stability and they consist of the FCC matrix phase and gamma' precipitated phase with L12 structure, in which the FCC matrix is rich in Fe, Co, and Cr, while the gamma' precipitates rich in Ni and Al. The changes of the precipitates of the alloys with the aging time are divided into two stages. In the first stage (the aging time is 6 h, 12 h, and 24 h), the volume fraction of the precipitates of HEAs increases initially, but when the durations beyond 12 h, the size of it gradually increases but the volume fraction of the precipitates decrease. After the durations beyond 48 h, the alloy will undergo secondary precipitation effect again but the volume fraction of the reprecipitated phases is lower, and the precipitates gradually coarsen with the increase of durations. All the HEAs occurred abrasive wear and oxidative wear during the wear process. In addition, delamination wear and spalling wear occurred on the 6hHEA and the 168hHEA, respectively. The 12hHEA has the best wear properties due to the highest volume fraction and the uniform distribution of the precipitates. Our study indicates that the alloys can have good wear properties inducing a certain volume fraction of L12 precipitated phase by proper heat treatment, and it can provide theoretical reference for the development and design of the alloys with good wear resistance.