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 γ–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.