Transition metal silicide based refractory composite alloys have great potential for applications as the next generation of turbine airfoil materials, due to their significantly higher operating temperatures than advanced Ni-based superalloys. In order to achieve the most of refractory silicide based materials, multi-component alloying has been considered to be the most useful route for developing alloys of a good balance of creep resistance, fracture toughness, oxidation resistance, and room-temperature ductility. In this work, structural stabilities of disilicides of the group IVB to VIB transition metal elements are studied using the ab initio density functional theory, shedding light on alloying/bonding behaviour at the electronic level. The results are also useful for developing full thermodynamic databases using the CALPHAD approach, where lattice stabilities of counter-phases are critical for accurate thermodynamic descriptions of multi-component systems.