On the Interactions Between γ-Al2O3 Nanoparticles and Primary or Eutectic Al2Cu in Hypereutectic Al-Cu Alloy

Numerous studies have extensively documented models aimed at predicting the likelihood of nanoparticles (NPs) being either pushed away or engulfed by the liquid-solid interface of Al dendrites in Al melts, such as those found in hypoeutectic Al-Si and Al-Cu alloys. However, these models often do not consider the effect of the solid-phase growth style on the interaction between NPs and the liquid-solid interface, given that Al dendrites typically only exhibit a continuous growth style attributed to a non-faceted growth mechanism. Yet, what occurs when the solid phase exhibits different growth styles? In this work, the behaviors were found to be different when gamma-Al2O3 NPs came across eutectic non-faceted Al2Cu or primary faceted Al2Cu in a hypereutectic Al-Cu alloy. Specifically, the NPs can be engulfed by eutectic Al2Cu but be pushed away by primary Al2Cu. It is supposed that the Jackson alpha factor should be considered when building theoretical models to predict the interactions between nanoparticles and liquid-solid interfaces.