Effect of kinetics on P removal by Al-Si solvent refining at low solidification temperature

•A high removal rate of P in refined Si in Al-Si-P system is confirmed.•An apparent segregation coefficient is introduced to characterize the process.•P contents in primary Si controlled by thermodynamic factors are evaluated.•Critical effect of kinetic factors on P removal at low temperature is confirmed.

To determine the effect of kinetics on P removal in Al-Si-P system, three sets of experiments with different solidification temperature ranges have been carried out. High P removal rates can be confirmed. An apparent segregation coefficient is introduced to characterize the P removal in this Al-Si-P system, which are determined to be 0.0207, 0.00822 and 0.00679, when the cooling rate is 0.556 mK·s−1 and the Si contents in the melt are 39.1, 29.3, 19.4 at.%, respectively. Theoretical P contents in the primary Si phase controlled by thermodynamic factor (X¯PinprimarySiT) and theoretical P contents in the primary Si phase controlled by kinetic factor (X¯PinprimarySiK) are calculated. The results reveal that the kinetic factors have critical influence on P removal at low solidification temperature.