Effect of solidification cooling rate and phosphorus inoculation on number per unit volume of primary silicon particles in hypereutectic aluminium—silicon alloys

Abstract

Collected data on derived number per unit volume $\bar N_V$ of primary silicon particles in hypereutectic Al-Si alloys show a power relationship with solidification cooling rate $\dot T$ of the form $\bar N_V=A\dot T^n$ where typically $n \sim 1$ and $A \simeq 130$ mm^-3 (K/s)^-1 in the absence of phosphorus and $A \simeq 720$ mm^-3 (K/s)^-1 in its prescence. Significantly lower apparent values of $\bar N_V$ from one set of results appear to stem from measurement of a mean long dimension rather than diameter of particle sections as well as lower measured undercoolings than in Bridgman experiments at similar $\dot T$.