Formation of MgAl2O4 at Al/MgO interface

Abstract

Undercooling and wetting angles of liquid aluminum solidified on single crystal MgO substrates, with specific orientations MgO(100), MgO(110) and MgO(111), are measured. The measured undercooling is observed to be less sensitive even though the lattice misfits provided by the substrates are significantly varied. Transmission electron microscopy analysis reveals formation of MgAl2O4 layer at Al/MgO interface. It has higher potency to act as nucleation substrate for Al and responsible for identical undercooling values for substrates with different lattice mismatch. The higher wetting angle for MgO(110) and MgO(111) surfaces with liquid Al is attributed to surface reaction at higher temperature.