Relationships between composition and properties of (Cr/Ti)SiN and (Cr/Ti)CN alloys: an ab initio study.

It has previously been noted that different fcc metal nitrides exhibit different superior properties, including the high hardness of TiN and the excellent corrosion and oxidation resistance of CrN. Si and C have been added into such metal nitrides in order to tailor their functional properties. Contrary to the intensively studied TiSiN and TiCN nanocomposite and solid solution systems, much less is known about the complex relationships between the composition and the properties of CrSiN and CrCN. In fact, there is a qualitative difference between cubic spin-unpolarized materials such as TiN, and spin-polarized materials such as CrN which may exhibit a cubic/orthorhombic structural transformation. In the present work, we report ab initio calculations of the properties of (Cr/Ti)SiN and (Cr/Ti)CN systems of various compositions. We specifically predict the lattice constant, bulk modulus, elastic tensor, shear modulus, Young's modulus, Poisson's ratio, magnetization, electronic structure and preference towards the cubic/orthorhombic structural transformation. Knowledge of the modeled relationships allows one to tailor the material characteristics of various ternary metal nitrides for different technological applications.