Mechanically activated self-propagating high-temperature synthesis of titanium silicide-molybdenum disilicide composite using constituent elements

Abstract

Silicides with potential to form a protective silica layer have garnered considerable attention as engineering ceramic materials. This research investigates the influence of initial composition and mechanical activation on the synthesis performance and microstructure of products in the Ti–Si–Mo system. Several compositions, including Ti8Mo29Si63, Ti15Mo25Si60, Ti22Mo22Si56, Ti40Mo12Si48, Ti52Mo6Si42, Ti62.5Si37.5, and Mo33Si67, were prepared and synthesized via mechanically activated self-propagating high-temperature synthesis (MASHS). XRD, SEM, and EDS analyses, along with related investigations such as grain size calculations and morphology studies, were performed. The results indicate that at low Ti concentrations, the composite contains (Ti0.8,Mo0.2)Si2 and MoSi2, whereas moderate Ti concentrations enable the formation of the MoSi2–Ti5Si3 composite. Moreover, a high amount of Mo can extensively dissolve into the titanium and titanium silicide structure, resulting in the synthesis of the (Ti,Mo)5Si3 phase in Ti-rich samples. The dissolution of Mo in the crystal structure of the compound decreases the lattice parameters of titanium silicide. Furthermore, mechanical activation facilitates the initiation of reactions in compositions with lower Ti content and yielding fine-grained products.

Keywords

• Molybdenum disilicide (MoSi2)
• Titanium silicide (Ti5Si3)
• Self-propagating high-temperature synthesis
• Solid solution
• Composite compounds