Growth -microstructure relationship in MgO-MgAl2O4 eutectic fabricated by micro -pulling down method with MgAl2O4 seed crystals

The MgO-MgAl2O4 eutectic was directionally solidified via micro-pulling down method in the form of rods with 2-3 mm diameter. MgA1204 single crystals (with < 111 > orientation) were used as crystallization seeds. At low pulling rates, especially 0.15 mm/min triangle-like cross-section was observed, which was linked to the eutectic MgAl2O4 following the crystallographic direction of the seed. MgO precipitates in the form of lamellae and rods with median equivalent diameter ranging from 0.19 to 0.85 mu m, depending on the pulling rate. The preferred crystallization direction was < 111 > for both phases, however notable traces of other directions, e.g. < 100 >, < 110 > and < 331 > were found as well.