Microstructure and mechanical properties of AlTiN/MoVCuN nano-multilayered coatings deposited by BPMS

AlTiN/MoVCuN nano-multilayered coatings were prepared by using bipolar pulse magnetron sputtering (BPMS), and the effect of rotation speed on the microstructure, chemical composition, and mechanical properties was explored. The results revealed that AlTiN/MoVCuN nano-multilayered coatings exhibited a dense columnar crystal structure, and the microstructure became much denser at higher rotation speeds. All the multilayered coatings showed a double-phase structure of c-TiAlN and B1-MoVN, with the absence of Cu-associated phases due to the low Cu contents. As the rotation speed increased, the crystallinity of the coatings gradually improved and the grain size also increased. Due to a small modulation period (Lambda <= 1.0 nm), the coatings showed a typical epitaxial growth structure, where AlTiN and MoVCuN layers grew epitaxially with each other. With increasing the rotation speed, the compressive residual stress initially increased, and then decreased slightly. The highest hardness of 31.8 GPa was achieved at 3 rpm, attributing to the microstructure densification, high residual stress, and low Cu content.