Comprehensive investigation of the physical properties of X5SiC2 (X = Cr, Mo, W) silicides: A first-principles approach for high-temperature applications

Structural, mechanical, elastic anisotropy and thermo-physical properties of X5SiC2 (X = Cr, Mo, W) silicides are explored using ab-initio calculations. All three X5SiC2 silicides satisfy the mechanical stability conditions. Calculated mechanical properties reveal that among the silicides Cr5SiC2 has the stiffest mechanical structure and greatest shear deformation resistance. According to Pugh and Poisson's ratio, all three silicides exhibit a ductile nature. Shear anisotropy factors (A1, A2, A3), compressibility anisotropy (AB), shear anisotropy (AG), and universal elastic anisotropic index (AU) results show the anisotropic nature of ternary X5SiC2 (X = Cr, Mo, W) silicides. Examined silicides show strong mechanical anisotropic behavior. Among the X5SiC2 (X = Cr, Mo, W) silicides, Cr5SiC2 exhibits the highest Debye temperature, thermal conductivity and melting temperature. Thermodynamic properties (Debye temperature, lattice heat capacity, bulk modulus, cell volume and thermal expansion coefficient) are also calculated at different temperatures and pressures. Mechanical and thermophysical properties suggest that X5SiC2 silicides could be used in thermal barrier coatings (TBCs), heat storage devices, aero-engines and gas turbine blades. The combination of calculated results for X5SiC2 silicides display the promising suitability of these materials to use for high temperature applications.