Effect of Ultrasonic Impact Treatment on the Friction and Wear Properties of Al2FeCoNiCrW0.5 High Entropy Alloy Coatings

In order to investigate the influence of ultrasonic impact treatment (UIT) on the friction and wear properties of Al2FeCoNiCrW0.5 high-entropy alloy coatings， these coatings were prepared on the 45 steel substrate by a laser cladding process.The coatings were subjected to UIT for 5 and 10 min， and the microstructure， microhardness and friction and wear characteristics of the high entropy coatings were evaluated under varying ultrasonic impact times.Results indicated that the coating was composed of BCC phase and FCC phase， and the phase structure of the coating remained unchanged before and after ultrasonic impact treatment.After treatment by ultrasonic impact，the coating grains were refined and locally reached nanocrystalline size.Within 10 min， the increase of ultrasonic impact time improved the hardness of the coating continuously， and the maximum surface microhardness was 893 HV0.5.Under the same friction and wear test conditions， the wear volume of the coating treated with ultrasonic impact for 10 min was 3.391 mm3， and the wear resistance was improved by 20%compared with the coating without ultrasonic impact treatment.Moreover， the wear mechanism of the high entropy alloy coatings before and after ultrasonic impact treatment changed from abrasive wear， oxidative wear and adhesive wear to abrasive wear and oxidative wear.In general， ultrasonic impact treatment could effectively improve the friction and wear properties of high entropy alloy coatings.