Theoretical prediction of structural, elastic and electronic properties of Si-doped TiCuGe intermetallics

The structural, elastic and electronic properties of TiCuGe1−xSix alloys (x = 0, 0.25, 0.5, 0.75 and 1) were investigated by means of first-principles calculations within the framework of density functional theory (DFT). The calculated results demonstrate that the partial substitution of Si with Ge in TiCuGe leads to a decrease of lattice constants, and the optimized structural parameters are in agreement with the available experimental values. The results of electron density are compared with the theoretical and experimental data from the literature. From energetic point of view, it is found that with increase of Si content the structural stability of TiCuGe1−xSix compounds increases apparently. The single-crystal elastic constants are obtained by computing stress–strain function according to Hooke's law, and then the bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν of polycrystalline aggregates are derived. The calculated results show that among the TiCuGe1−xSix alloys, TiCuGe0.75Si0.25 exhibited the largest stiffness, while TiCuGe0.25Si0.75 showed the best ductility. Finally, the electronic density of states (DOSs) are further studied and discussed.

► The optimized structural parameters agree with available values.
► Structural stability increases with increasing Si content.
► TiCuGe0.75Si0.25 exhibits the largest stiffness.
► TiCuGe0.25Si0.75 shows the best ductility.