Phase and Microstructural Analysis of In-Situ Derived Alumina-TiB2 Composites

The paper focusses on the phase and microstructural evolution in ceramic composite based on alumina and titanium diboride, in which the precursor materials are aluminium mixed with TiO2 and B2O3. The highly exothermic, self-sustaining, and aluminothermic reaction (103Al+TiO2+B2O3=53Al2O3+TiB2,ΔH=2,710kJmol) occurs in the absence of oxygen. Eventually, triggering the self-sustaining reaction on compacts formed from a ball-milled derived mixture, consisted of Al particles coated with TiO2 and B2O3 nano-particles, resulted in the spontaneous formation of a ceramic phase mixture consisted of alumina particles coated with TiB2 and Ti2O3 nano-particles. The highly exothermic character of the reaction enabled the sintering of the coated Al2O3 particles into a dense unique microstructure.