Boron carbide - silicon carbide composite was produced by mechanically activated combustion synthesis (MASHS) method, in this study. Initially, raw materials powders containing B₂O₃, Si, C and Mg were weighed and were milled under Ar atmosphere by a planetary mill. For prepare pellets, the milled powders were pressed by uniaxial cold press and synthesis was occurred in atmosphere controlled tubal furnace. In the various steps, XRD analysis was taken to check the phases. XRD analysis used to calculate the average crystalline size and SEM and TEM analysis were taken to morphology studying. Resulting product is contains MgO, B4C and SiC. Also in the XRD analysis little chance
 
existence of Mg₂SiO₄ or borate compounds of magnesium and remaining boron, carbon and silicon are outstanding. In order to remove or reduce undesired phases, acid leaching by hydrochloric and mechanical activation with different energies were performed. The study of X-ray diffraction analysis after acid leaching showed great influence of acid leaching by HCl to remove impurities. It was also seen that remaining substances significantly reduced by activation energy increases. Average crystalline sizes of optimal sample were calculated by Scherrer equation by 11.09 for B4C and 12.66 for SiC. The SEM and TEM analysis confirmed synthesis of nanoscale boron carbide - silicon carbide composite in nano scale. Grain size of about 30 nm was observed by TEM.