Characterization of nanocrystalline AlTiN coatings synthesized by a cathodic-arc deposition process

Graded and multilayered AlxTi1−xN nanocrystalline coatings were synthesized by using cathodic-arc evaporation (CAE) process. Ti33Al67 and Ti50Al50 alloy cathodes were used for the deposition of AlxTi1−xN nanocrystalline coatings with different Al/(Ti+Al) ratios. Optical emission spectra of the plasma species including atomic and ionized Ti, atomic Al, excited and ionized nitrogen (N2 and N2+) revealed that the excitation, ionization and charge transfer reactions of the Al–Ti–N plasma occurred during the AlxTi1−xN coating process. A preferred (111) orientation was shown in the Al0.67Ti0.33N with high Al/(Ti+Al) atomic content ratio (0.63) and small grain size (29 nm). The graded Al0.67Ti0.33N/TiN possessed the highest hardness of Hv25 g 3850 ± 180. However, the multilayered Al0.67Ti0.33N/TiN coating supported a longer tool life with lower residual stress. It has been found that the wear performance and mechanical properties of the films were correlated with the Al/(Ti+Al) content ratio and multilayered structure.