Of Mgb <sub> 2 </ Sub> Superconducting Materials Synthesis Process

MgB₂ and RE-MgB₂ superconductive materials were produced by means of mechanical alloying and solid sintering reaction respectively. The processes mechanical alloying and solid reaction synthesis in the Mg-B system and sintering technology, oxidation behavior and the effect of rare earth doping on MgB₂ were investigated systematically by means of SEM and X-ray diffraction technique.Some microcrystalline and amorphous MgB₂ can be achieved in the Mg-B binary system (Mg:B=1 :2) induced by mechanical alloying (MA). The formation mechanism of MgB₂ by MA is diffusion solution. The speed of mechanical alloying were different under different ball milling conditions such as the quality's rate of ball to powder, the milling time, the kinds of ball. The quality's rate of ball to powder is a decisive factor. Protecting Mg volatility and oxidized at elevated temperature and avoid MgB₂ decomposing at high temperature are the key factor of formation MgB₂ by solid-state sintering reactions, so the sintering must process under protect gas or vacuum. The sample which was prepared by mixed Mg and B with a atom ratio of Mg:B=1:1.5 must be held at 800℃ for 2h in a flowing atmosphere of Ar. However, to vacuum seal the sample which was prepared by mixed Mg and B with a atom ratio of Mg:B=1: 1.95 in a quartz , then held the sample at 800℃ for 1h is another synthesis method. The product must be powdered, compacted and reheated, and the density of MgB₂ can be raised. The additives of the rare earth (Y, Pr) were solution phase in MgB₂ and have not evident effect on MgB₂!s microstructure. The additives of the rare earth increase the density of the sintered MgB₂.