Study of the sintering behaviour of MgB2 superconductor during hot-pressing

The densification behaviour of MgB2 was studied when commercial powder was hot-pressed in the temperature range 1070-1190 deg C. The mechanisms active during sintering were investigated by continuously recording the shrinkage vs. time and elaborating the data on the basis of Kingery's model for liquid phase sintering. XRD and SEM analysis on final dense bodies were used to evaluate secondary phases formation during sintering and the effect of magnesium sublimation. AC magnetic susceptibility measurements were also performed to correlate the microstructural and morphological modifications induced by hot-pressing and the superconducting properties.