Structural and elastic properties of ternary silicides ScTSi (T═Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) and of the equiatomic intermetallic compounds YTX (T═Ni, Ir and X═Si, Ge, Sn, Pb)

The structural and elastic properties of the ternary silicides ScTSi (T═Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) and of the equiatomic intermetallic YTX (T═Ni, Ir; X═Si, Ge, Sn, Pb) are studied using the density‐functional theory considering the orthorhombic TiNiSi crystal structure with space group Pnma. From the calculated formation energy, we obtained the following stability order of: ScCuSi < ScCoSi < ScRuSi < ScNiSi < ScPdSi < ScRhSi < ScIrSi < ScPtSi and YNiPb < YNiSn < YNiGe < YNiSi < YIrSn < YIrGe < YIrPb < YIrSi. The lattice parameters and atomic positions are in good agreement with experiments to ∼1%. All the alloys are mechanically stable using the Born elastic stability criteria. Ductile behavior inferred from the Pugh ratio, shear over bulk modulus G/B , and the Cauchy pressure, could be observed only for ScTSi (TRu, Pd, Pt) and YNiSn compounds and moderately for YIrX (Si, Ge, and Sn) and YNiPb. On the contrary, ScTSi (TCo, Ni, Cu, Rh, Ir), YNiGe, and YNiSi compounds are covalent or exhibit G/B  > 0.5, leading to a brittle behavior in accordance with the Poisson ratio value. The Zener anisotropy factor is different from 1, indicating that these compounds are elastically anisotropic materials. A strong correlation is found between G and the Young's modulus E , slightly above G ∼(3/8) E widely found for polycrystalline metals. Correlation trend between the Young's modulus E and the shear modulus G of intermetallic compounds.