Diffusion bonding of alumina-alumina via in-situ Ti5Si3 interlayers formed by self-propagating high-temperature synthesis in spark plasma sintering

Joining alumina is challenging due to its brittleness and chemical inertness. This study presents a hybrid approach combining combustion synthesis (CS) of Ti-Si with spark plasma sintering (SPS) to achieve alumina-alumina diffusion bonding via in‑situ formation of Ti 5 Si 3 ‑based interlayers. Dense and reproducible joints were obtained at 1300 °C and 67 MPa using pre‑pressed Ti-Si pellets and fine titanium powder. SEM/EDS and XRD confirmed effective diffusion bonding and the formation of Ti‑based intermetallic phases, with preferential aluminium diffusion into the interlayer. Nanoindentation revealed mechanically coherent, multiphase interlayers with properties consistent with Ti, Ti-Al intermetallics, and Ti silicides. The self‑sustaining CS reaction reduces energy input and dwell time, highlighting this method as a fast and scalable route for joining alumina ceramics.