B4C-SiC composites were produced using spark plasma sintering (SPS) both reactively from B4C-SiO2-C starting powders and directly from B4C-SiC at 1700 and 1750 degrees C under a pressure of 40 MPa. Densification, microstructure and mechanical properties of B4C-SiC composites were investigated. 98.8% relative density was obtained with the addition of Y2O3 in directly spark plasma sintered sample containing 10% SiC at 1750 degrees C for 5 min. In reactive spark plasma sintering, increasing SiC content resulted in a decrease in density because of the oxidation of SiC to SiO gas phase. The glassy phases formed with Y2O3 addition caused the Vickers hardness values to increase. SiC phase showed a homogenous dispersion in B4C matrix. (C) 2012 Elsevier Masson SAS. All rights reserved.