Nanoscale architecture of (CrN/ZrN)/(Cr/Zr) nanocomposite coatings: Microstructure, composition, mechanical properties and first-principles calculations

Abstract The main principles of formation of microstructure and properties of the nanostructured films consisting of periodically alternating multilayers of CrN/ZrN transition metal nitride films and Cr/Zr pure metals were investigated. First-principles calculations were carried out to give more insight in the physics of the strength enhancement of the deposited coatings. A special coating architecture, which consisted of 7 metallic and 40 nitride bilayers in each modulation period, was developed and then used. The thickness of single metallic bilayer was 16 nm, while the thickness of nitride bilayer was 25 nm. Microstructure studies showed mainly the presence of cubic CrN and ZrN with (200) and (111)/(200) preferential orientations, respectively. The analysis of the defect structure near the CrN and ZrN layer interfaces revealed the presence of dislocations, despite the small size of nanolayers and nanocrystallites, and the disorientation of the planes of nanocrystallites. The maximal hardness, reduced elastic modulus, elastic strain prior to plastic deformation and resistance to plastic deformation of the nanocomposite (CrN/ZrN)/(Cr/Zr) coatings were reached 34 GPa, 330 GPa, 0.1 GPa and 0.36 GPa, respectively, due to the multilayer-in-multilayer design and structural peculiarities of experimental coatings.