Prenucleation at the metal(l)/oxide(s) interfaces investigated by ab initio calculations
Tuesday, June 20, 2023, 4:00 PM - 5:30 PM
Max Bell Foyer
Changming Fang
Above the nucleation temperature, there is atomic ordering in the liquid nearby a liquid/solid interface, which is referred to as prenucleation. Prenucleation produces a precursor for heterogeneous nucleation in the liquid and thus, plays a crucial role in the nucleation process. Oxide particles including magnesia, spinel and alumina are inevitably formed in the liquid light-metals during liquid metal handling and casting. The indigenous oxide inclusive has influences on the mechanical properties of cast parts. Moreover, they may act as nucleation sites for potential grain refinement. Understanding of prenucleation at liquid-metal/oxide interfaces is a prerequisite for controlling heterogeneous nucleation during casting. Here, we present the recent ab initio studies on prenucleation at the liquid-metal/oxide interfaces. We revealed a rich variety of interfacial chemistry and identified the formation of a metal layer terminating the oxide substrates in liquid light metals. The terminating metal atoms are positively charged and topologically rough, which impacts strongly the prenucleation at the interfaces. We also presented studies of segregation effect of Group III elements on prenucleation at L-Al/γ-Al2O3 interfaces, which opens a path to modify potency of the substrate surfaces via impurity segregation to manipulate the solidification of light metals.