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.