First-principles prediction of structure and mechanical properties of TM5SiC2 ternary silicides

Although transition metal silicides are promising advanced functional materials, the adjustment of strength and ductility behavior is a great challenge. It is believed that the introduction of C element maybe improved the overall properties of transition metal silicides. Similar to the TM5SiB2, the structure, elastic properties and ductility of TM5SiC2(TM = Cr, Mo, Nb and W) ternary silicides are studied by the first-principles calculations. The results show that four novel TM5SiC2 ternary silicides are firstly predicted. Compared to TM5Si3, these TM5SiC2 ternary silicides have strong elastic deformation resistance due to the role of C element. In particular, these TM5SiC2 ternary silicides also exhibit better ductility compared to the brittle TM5Si3 phases. The calculated electronic structure shows that these TM5SiC2 ternary silicides have electronic properties because of the band overlap of C-2p state and TM-d state near the Fermi level. Therefore, this work can provide a new path to improve the mechanical properties of TM-Si-C ternary silicides high-temperature materials. •Four novel tetragonal TM5SiC2(TM = Cr, Nb, Mo and W) ternary compounds are first predicted.•The TM5SiC2 ternary silicides shows strong bulk elastic modulus compared to the TM5Si3.•The TM5SiC2 ternary silicides shows better ductile compared to the TM5Si3.•The TM5SiC2 ternary silicides show better thermodynamic properties.•The TM5SiC2 ternary silicides show better electronic properties due to the role of C-2p state.