Micro-mechanical investigation of (Al50Ti50)N coatings enhanced by ZrN layers in the nanolaminate architecture

A series of nanolaminate (Al50Ti50)N/ZrN coatings with different modulation period (lambda) and bias voltage were synthesized by vacuum arc deposition (VA-PVD). The composition, evolution of the microstructure, and mechanical properties were studied during the transition from the basic monolayer (Al50Ti50)N coating to the nanolaminate architecture with a stepwise decrease in the modulation period. XRD and HR-TEM results showed that the binary layer in (Al50Ti50)N/ZrN nanolaminates composed of fcc-(Ti, Al)N phase with the (1 1 1) preferred orientation of crystallite. The isostructurality of fcc-(Ti, Al)N and Bl-ZrN lattices contributed local epitaxial grain growth in multilayer nanolaminate. ZrN layers, as the second component of the bilayer, had a highly textured structure with a predominant texture axis (1 1 1). The maximum values of nanohardness of 26.5 GPa and elastic modulus of 287.3 GPa were obtained for the sample with the lowest modulation period of about 15 nm. According to the results of chemical analysis by XPS, we established the oxidized state of all elements of the metal component of the surface layer, such as ZrO, TiON, ZrNO, and the presence of TiN, TiNx, ZrN nitride compounds.