CRYSTALLIZATION OF MGO-B2O3-SIO2 SLAG OBSERVED BY IN-SITU TEM

Transmission electron microscopy (TEM) observation of in situ heated M gO-B2O3-SiO2 slag allowed the description of its dynamic crystallizati on process. The crystallization processes are constituted by two steps : (i) phase separation and (ii) nucleation and growth of 2MgO . B2O3 c rystal precipitated prior to 3MgO . B2O3. The crystallization processe s are sensitive to the electron beam. In electron irradiated regions, the phase separation occurred at 300 degrees C, however, the phase sep aration was observed in the electron non-irradiated region at about 75 0 degrees C.