First-principles investigation of phase stability, elastic and thermodynamic properties in L1₂ Co₃(Al,Mo,Nb) phase

First-principles calculations have been performed to investigate the phase stability, elastic, and thermodynamic properties of Co₃(Al,Mo,Nb) with the L1₂ structure. Calculated elastic constants show that Co₃(Al,Mo,Nb) is mechanically stable and possesses intrinsic ductility. It is found that the shear and Young's moduli of Co₃(Al,Mo,Nb) are smaller than those of Co₃(Al,W). Calculated density of states indicate the existence of covalent-like bonding in Co₃(Al,Mo,Nb). Temperature-dependent thermodynamic properties of Co₃(Al,Mo,Nb) can be described satisfactorily using the Debye-Grüneisen approach, including entropy, enthalpy, heat capacity and linear thermal expansion coefficient, showing their significant temperature dependences. Furthermore the obtained data can be employed in the modeling of thermodynamic and mechanical properties of Co-based alloys to enable the design of high temperature alloys.