Exploration of transition metal carbides TMCs (TM = V, Ti and Zr): mechanical, electronic structures and thermodynamic properties

Abstract

The structural, mechanical, electronic, minimum thermal conductivity, tensile and thermodynamic properties of TMCs (M = Ti, V and Zr) have been investigated through first-principles calculations combination with QHA based on density-functional theory. The formation enthalpy, phonon spectrum and elastic constants emphasise that all TMCs are thermodynamically and mechanically stable. The elastic moduli of the VC are higher than the fourth group (TiC and ZrC). The strong covalent bonding between VC is the main reason for the high mechanical properties, while the ionic bonding of ZrC would explain for its low strength. Meanwhile, the weaker mechanical anisotropy of the TMCs favours a higher damage tolerance. Furthermore, the calculated minimum thermal conductivity in different directions of the TMCs demonstrated that is anisotropic. Finally the temperature dependence of thermodynamic parameters including volume, thermal expansion coefficient, bulk modulus and specific heat capacity at constant pressure is evaluated to be stable based on the QHA method.