First-principles study of ZrC x N1−x alloys with electron concentration modulation

The structural and mechanical properties of the ZrC x N1−x alloys with electron concentration modulation were systematically investigated by using the pseudopotential plane wave method within the generalized gradient approximation. The obtained equilibrium structure parameters and mechanical properties are in good agreement with the available experimental and other theoretical results. In addition, the theoretical Vickers hardness of ZrC x N1−x was calculated with the empirical formula. With an increase in carbon content in this alloys the hardness increases as carbon content up to 70 % then decreases a little, which has the same hardness change trend comparing with that of TiC x N1−x . Also, it was found that ZrC0.7N0.3 alloy with a valence-electron concentration of 8.3 per unit cell possesses the greatest hardness among the whole composition range. Furthermore, the analysis of electronic properties revealed the metallic character of ZrC0.7N0.3 alloy. The thermodynamic stability of the designed alloy was also estimated by the calculated mixing enthalpy.