Experimental study on phase formation of SiC doped MgB2: processing of Mg-B-SiC powders by spark plasma sintering

In order to study the effect of spark plasma sintering (SPS) technique synthesis SiC-MgB2 on the phase formation, the MgB2 and SiC-MgB2 bulks were fabricated with mixed powders by various SPS synthesis routes. The phase formation processes were investigated with the aid of X-ray diffraction analysis, TEM investigations and sintering theories. The solid-solid reaction between Mg and B powders formed MgB2 at low temperature. As the sintering temperature increases, the reactions of molten Mg with B form MgB2, and simultaneously, the molten Mg promotes the decomposition of SiC and nuclei of Mg2Si may form on the surface of SiC grains; the nascent MgB2 incorporates the carbon into lattice, hereby enhancing the SiC decomposition. The experimental results are in good agreement with the assumed chemical reaction.