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

Abstract

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.