Microstructure and mechanical properties of nanomultilayered AlTiN/Cu coatings prepared by a hybrid system of AIP and PDCMS

Due to its excellent lubricity and immiscibility with nitride phase, Cu has been added to nitrides to form a typical nanomultilayer structure. In this work, a hybrid deposition of AIP and PDCMS was applied to synthesize the multilayered AlTiN/Cu coatings, and the relationship between microstructure and mechanical properties was explored. The Cu-free AlTiN coating exhibited a c-TiAlN phase with a strong (200) preferred orientation. After adding Cu layer, the microstructure changed from a dense columnar structure into a featureless structure and then a fine-grained structure. As the Cu layer thickness reached 5.1 nm, the AlTiN/Cu(18.4 at.%) coating showed a double-phase of c-TiAlN and c-Cu. The thickness modulation period of Cu/AlTiN sublayer exhibited an excellent linear relationship with the content ratio of Cu/(Al + Ti). After adding Cu, the ion bombardment effect was weakened, the AlTiN/Cu(2.9 at.%) coating exhibited the lowest surface roughness of 18.9 nm, and the hardness gradually decreased from 34.6 to 13.2 GPa, accompanied by a relaxation of residual stress. Due to a high H/E* ratio, a maximum adhesion strength of 83.0 N was obtained at 2.9 at.% Cu.