Nitride wear resistant coatings are widely used in the cutting and forming tools due to their high corrosion and hardness, great wear resistance as well as good thermal stability.Recent researches have fully demonstrated the potential of first-principles calculations in understanding the material properties at the nanoscale.Here, we present a systematic overview of alloying trends when early transition metals (Y, Zr, Nb, Hf, and Ta) are added in the TiN system, routinely used as a protective hard coating.Supercell method was used to model Ti1-xTMxN (x=0, 0.25, 0.5, 0.75, 1) alloys with cubic rock-salt B1 structure.The calculated results of lattice constants were in good agreement with the experiment data and theoretical results.The alloyed lattice parameters tend to be larger than the corresponding linearized Vegards estimation.The three independent elastic constants C11, C12, C44 of Ti1-xTMxN systems were calculated and the polycrystalline aggregates elastic properties, such as bulk modulus B, shear modulus G, Youngs modulus E, anisotropy ratio A and Poissons ratio v were determined by using the Voigt-Reuss-Hill (VRH) averaging scheme.In addition, the electronic density of states (DOSs) of binary nitrides in Ti1-xTMxN system was also calculated to demonstrate the hybridization state and bonding configuration, to further elucidate the role of individual elements.Finally, mixing enthalpy as a measure of the driving force for decomposition into the stable constituents is enhanced by adding Y, Zr and Hf, suggesting that the onset of spinodal decomposition will appear in these cases for lower thermal loads than for Nb and Ta alloyed Ti1-xTMxN.