Adhesion and nonwetting-wetting transition in the AlÕa-Al2O3 interface

Using a reactive force field ~ReaxFF!, we investigated the structural, energetic, and adhesion properties, of both solid and liquid Al/a-Al2O3 interfaces. The ReaxFF was developed solely with ab initio calculations on various phases of Al and Al2O3 and Al-O-H clusters. Our computed lattice constants, elastic constants, surface energies, and calculated work of separation for the solid-solid interface agree well with earlier first-principles calculations and experiments. For the liquid-solid system, we also investigated the nonwetting-wetting transition of liquid Al on a-Al2O3(0001). Our results revealed that the evaporation of Al atoms and diffusion of O atoms in a-Al2O3 lead to the wetting of liquid Al on the oxide surface. The driving force for this process is a decrease in interfacial energy. The nonwetting-wetting transition was found to lie in the 1000–1100 K range, which is in good agreement with sessile drop experiments.