Influence of static magnetic field on the heterogeneous nucleation behavior of Al on single crystal Al2O3 substrate

Abstract

This paper investigates the heterogeneous nucleation behavior of Al on single crystal Al2O3 substrate under the influence of static magnetic field (SMF). The nucleation temperature of the Al melt on the substrate was measured to decrease ~2.9°C under SMF, i.e. the undercooling was enhanced with the application of SMF. Using electric back-scatter diffraction (EBSD) and high-resolution transmission electric microscope (HRTEM), the interfacial crystal orientation matching of Al/Al2O3 was found to change dramatically, from {110}[011]Al~//{101¯0}[0001]Al2O3 without SMF to ~11.4o between {110}[1¯12]Al and {101¯0}[0001]Al2O3 under SMF, indicating that the SMF can increase the lattice misfit of Al/Al2O3 interface. The lattice matching deviation caused by SMF was supposed to lead to the increase of interfacial free energy of the nucleus/substrate interface, and thus the formation of critical nucleus and the undercooling were modified. The results demonstrate that SMF is capable of influencing the heterogeneous nucleation behavior of the melt.