Reactive sintering of bulk multi-phase ceramics based on LaB 6 -TiB 2 eutectic granules

Abstract

The multiphase composite ceramics with ТіB₂-Al₂O₃-based matrix and LaB₆-TiB₂ eutectic inclusions have been synthesised via reactive hot pressing of Al-В₂О₃-Ті-LaB₆-ТіB₂ powder. The sintered materials were characterised by X-Ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy. The intermediate melts of aluminium and boron oxide separated the inclusions and allowed the charge densification at 1600°C and 30 MPa during 16 min preserving the unique fibering microstructure of LaB₆-TiB₂ granules. An additional heat release due to exothermic reactions in Al-В₂О₃-Ті mixture caused the inclusions surface melting and led to La in Al₂O₃ dissolution and TiB₂ dendrites formation near the eutectic grain boundaries.

Keywords

Reactive hot pressing composites structure multiphase ceramics borides

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