Hard TiAlTaN coating by HIPIMS deposition for cutting tools: experiments, simulations and cutting tests

The quaternary Ti_xAl_yTa_zN system has demonstrated superior thin film properties compared to conventional Ti_xAl_yN coatings. Beyond the influence of Ta content, the deposition method plays a crucial role in determining the structural and mechanical characteristics of the films. In this work, high-power impulse magnetron sputtering (HiPIMS) was used to deposit dense, tough, and hard Ti_xAl_yTa_zN coatings with different compositions from composite targets. These coatings were compared with TiAlN films. The impact of Ta incorporation was investigated both experimentally and through numerical simulations. Thin film growth and composition were modeled using VirtualCoater™, which provided valuable insights into the role of Ta in enhancing film densification and clarified the link between target and film compositions. Subsequent experimental characterization of mechanical, structural, and thermal properties revealed the significant advantages conferred by Ta addition. The improvements are attributed to: (1) enhanced hardness due to densification induced by energetic Ta ion bombardment, (2) stabilization of the cubic phase at elevated temperatures, and (3) improved thermal resistance through the formation of a homogeneous (Ti_xAl_yTa_z) oxide layer, in contrast to the Al₂O₃/TiO₂ bilayer typically observed in TiAlN coatings, as confirmed by XPS depth profiling. Finally, dry cutting tests confirmed a marked increase in tool life and improved surface finish of the machined components.