Influence of vacuum annealing on structures and mechanical properties of Al–Ti–N films deposited by multi-arc ion plating

• We prepared the Al–Ti–N nanocomposite films with high Al contents by multi-arc ion plating.
• We investigated the thermal stability and phase transformation of the Al–Ti–N films by vacuum annealing.
• We evaluated the hardness and adhesion strength of the Al–Ti–N films after vacuum annealing.

The Al–Ti–N films deposited by multi-arc ion plating have been annealed in vacuum within the range of 700–1100 °C. X-ray diffraction results showed that the structure of the films underwent the formation of coherent c-TiN and c-AlN for the annealing temperatures were up to 900 °C. A new phase AlTix (x = 0.50, 0.56, 3) was observed after annealing. The X-ray photoelectron spectroscopy results showed the intensity of Ti–Al bonds decreased as annealing temperatures increased, indicating the decomposition of (Al, Ti)N into c-TiN and c-AlN were at the expense of Ti–Al bonds. Differential scanning calorimetry experiments were used to investigate the dynamic behavior of the films during annealing process and the results showed that the N2 formed as a consequence of the phase transformation process. The release of the N2 resulted in the peeling of the films from the substrates. The film exhibited a maximum hardness of 39 GPa after 900 °C annealing due to the formation of coherent c-TiN and c-AlN phases. In addition, we also investigated the influence of vacuum annealing on adhesive strength.