A Study on Surface-Interface Regulation and Tribomechanical Performance: Al1-xCuxN Ternary Nitride Coatings

• The hexagonal phase of AlN films vanished upon alloying with Cu. • The activation energy was found to be 0.56 eV for Al 0.61 Cu 0.39 N films. • Cu addition facilitated the faradaic reactions in 1M Na 2 SO 4 electrolyte. • The red-shifting of N K-shell absorption edge revealed a change from N 3+ to N 2+ . • The hardness and corrosion resistance decreased with increasing Cu concentration. Al 1-x Cu x N (0≤x≤1) were deposited on Si (100) and quartz substrates by dc reactive magnetron sputtering at a substrate temperature of 150 °C. The present study investigated the morphology, structural, electrical, surface chemical, interfacial intermixing, electrochemical and tribo-mechanical properties of the Al 1-x Cu x N films. Surface morphology showed a linear trend in roughness assessments correlated with increasing Cu concentration. Alloying with Cu resulted in the disappearance of the hexagonal phase of AlN , showing an amorphous phase structure for the Al 0.76 Cu 0.24 N films. Surface chemical analysis of Al 1-x Cu x N films was carried out using X-ray photoelectron spectroscopy. The activation energy for the region I (0.09± 0.01 and 0.56± 0.1 eV) in the Arrhenius plots of Al 0.33 Cu 0.67 N and Al 0.61 Cu 0.39 N films were attributed to defect distribution. A decrease in the valency of N from 3 to 2, that is, N 3+ to N 2+ , was observed from the shifting of edge position towards lower photon energy of the N K-shell absorption edge. The resistance to oxidative degradation increased with the increasing Cu concentration in the Al 1-x Cu x N films. The increasing Cu concentration enhanced the galvanic corrosion, decreasing the overall corrosion resistance of Al 1-x Cu x N films. Al 0.76 Cu 0.24 N films exhibited the highest hardness and Young's modulus of 16.56 and 187 GPa, respectively. The average coefficient of friction (μ) for the Al 1-x Cu x N films increased from 0.08 to 0.21 with the increasing surface roughness.