Al2O3/B4C ceramic phase composite structure was produced by solid-state method. Transformations of ceramic phases, micromorphology were determined by employing X-ray diffraction, FT-IR, scanning electron microscopy and transmission electron microscopy (TEM). Transformation of ceramic phases was completed in a short time (6 h). Formation of Al2O3/B4C ceramic-phase powder mixtures was specified after leaching. As a result of the increase of mechanical energy and the amount of ceramic phase, reduction in powder particle size (50-350 nm) and increase in agglomeration tendency were observed. The impurities were removed after leaching and the distribution in which the ceramic phases are effective was obtained with the TEM study.