Fretting wear resistance of amorphous/amorphous (AlCrFeNi)N/TiN high entropy nitride nanolaminates

The application of amorphous high entropy ceramics as wear-resistant materials is limited due to their inherent brittleness at room temperature and strain softening during deformation. In order to overcome this limitation, we constructed amorphous/amorphous (AlCrFeNi)N/TiN nanolaminates with varying modulation period thickness by introducing a second amorphous phase through reactive radio frequency (RF) magnetron sputtering, along with corresponding monolithic amorphous films. Microstructure, mechanical properties, and tribological behaviors of the films were characterized wear in detail. Fretting wear results show that the nanolaminates with an average modulation period of 6 nm exhibited a wear rate of 2.8 times lower than that of the (AlCrFeNi)N film and 8.4 times lower than that of the TiN film. Further analysis using FIB-TEM revealed that the enhanced wear resistance of (AlCrFeNi)N/TiN nanolaminates was attributed to the high-density heterointerfaces. These interfaces inhibited the initiation and propagation of mature shear bands and acted as barriers to stress distribution. Additionally, the oxide composite layer at the interface demonstrated a synergistic effect through a mechanically induced tribo-chemical reaction, resulting in slight plastic deformation. For the amorphous (AlCrFeNi)N film, moderate wear resistance was achieved through the formation of transfer layer at the interface. For the amorphous TiN film, the dimensional stability of the film deteriorates due to the significant strain softening that occurs during deformation. This study deepens our understanding of the friction mechanisms involved in amorphous high entropy ceramics, offering valuable insights for the design of high damage-resistant materials.