Phase formation process of bulk MgB2 analyzed by Differential Thermal Analysis during sintering

In order to clarify the reaction process of bulk MgB2 phase, Differential Thermal Analysis (DTA), as the main measurement, was used to prepare bulk MgB2 samples and monitor the sintering reaction process. Combined with microstructure observation by SEM and X-ray diffraction analysis, the formation process of MgB2 phase was summarized. The reaction between Mg and B powders onsets before the melting point of pure Mg. The whole formation process of MgB2 includes two different stages: (1) solid-solid reaction stage, in which Mg and B powder cannot react completely and the growth of MgB2 grain is restricted by the pinning effects of pore; (2) solid-liquid reaction stage, in which the fused Mg promotes the reaction process and the regular hexagon bulky MgB2 grain forms by means of solution-reprecipitation and growth.