Rapid self-sustaining consolidation of titanium silicide (Ti ₅ Si ₃ ) via transient liquid phase reaction induced by an electric discharge

The fabrication of Ti ₅ Si ₃ in the form of a solid product directly from an elemental 37.5 at.% Si and 62.5 at.% Ti powder mixture was carried out by two different powder metallurgy routes. The first was by uniaxial pressing of the reactant powder mixture with sequent vacuum-sintering, and the second was by electric discharge sintering (EDS) of reactant powder mixture. The pressing process combined with vacuum-sintering produced a porous compact with multi phases of titanium silicide such as Ti ₅ Si ₃ , Ti ₅ Si ₄ , TiSi ₂ , and TiSi, including elemental Ti, which indicated an incomplete phase transformation into Ti ₅ Si ₃ . On the other hand, the EDS induced the phase transformation mostly into Ti ₅ Si ₃ with a small amount of Ti ₅ Si ₄ in <180 μsec, which had a sequent consolidation into a solid compact with an average crystallite size of 30.4 nm and a lattice parameter of a = 7.42 Å and c = 4.91 Å. The significantly higher hardness value of the EDS compacts can be the result of the high density and the fine microstructure stemming from the homogeneous dissolution of the elements and the constrained grain growth. The formation of Ti ₅ Si ₃ solid compact from the stoichiometric Ti and Si powder mixture by EDS can be dominated by the solid to liquid phase transformation mechanism.