Investigation on effect of alloying elements on mechanical properties of MoSi 2 by first principle calculation

The influence of substitutional alloying elements (Al, Nb and W) on the mechanical properties of MoSi₂ with both C11_b and C40 structures was explored by first principles calculations. Using the shear modulus/bulk modulus ratio (G/B), Poisson's ratio and Peierls stress, the change in the mechanical properties of the C40 and C11_b structured MoSi₂ due to the addition of the solute atom has been investigated. The results showed that the ductility of C11_b MoSi₂ was increased by alloying with the elements (Al and Nb) that form a C40 structured disilicide but decreased by alloying with the elements (W) that form a C11_b structured disilicide. In contrast, the effect of alloying elements on the ductility of C40 MoSi₂ showed a reverse trend to that of C11_b MoSi₂.