Microstructure and mechanical properties of (Ti,Al,Zr)N/(Ti,Al,Zr,Cr)N films on cemented carbide substrates

(Ti,Al,Zr)N/(Ti,Al,Zr,Cr)N bilayer films were deposited on cemented carbide (WC-8%Co) substrates by multi-arc ion plating (MAIP) using two Ti-Al-Zr alloy targets and one pure Cr target. To investigate the composition, morphology, and crystalline structure of the bilayer films, a number of complementary methods of elemental and structural analysis were used, namely, scanning electron microscopy (SEM), energy disperse X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Adhesive strength and mechanical properties of the films were evaluated by scratch testing and Vickers microindentation, respectively. It is shown that the resulting films have a TiN-type face-centered cubic (FCC) structure. The films exhibit fully dense, uniform, and columnar morphology. Furthermore, as the bias voltages vary from −50 to −200 V, the microhardness (max. Hv_0.01 4100) and adhesive strength (max. > 200 N) of the bilayer films are superior to those of the (Ti,Al,Zr)N and (Ti,Al,Zr,Cr)N monolayer films.