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 Co 3 (Al,Mo,Nb) with the L1 2 structure. Calculated elastic constants show that Co 3 (Al,Mo,Nb) is mechanically stable and possesses intrinsic ductility. It is found that the shear and Young's moduli of Co 3 (Al,Mo,Nb) are smaller than those of Co 3 (Al,W). Calculated density of states indicate the existence of covalent-like bonding in Co 3 (Al,Mo,Nb). Temperature-dependent thermodynamic properties of Co 3 (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. [ABSTRACT FROM AUTHOR]