Effect of rapid solidification on the microstructure and refining performance of an Al-Si-P master alloy

A new Al-18Si-2.5P master alloy has been successfully prepared to refine primary Si in hypereutectic A390 alloys, and the relationship between the microstructure and refining performance was investigated. The results show that as the solidification rate increases, the size of AlP particles in Al-18Si-2.5P master alloy reduces and the morphology of AlP evolves from plate-like to the fine nodular shape. The rapid solidification has a significant improvement on the refining performance and the P recovery of Al-18Si-2.5P master alloy. It is suggested that the difference in refining performance of Al-18Si-2.5P master alloy is related to the morphology, size and quantity of AlP particles in master alloy, which could influence the dissolution rate of AlP and thereby affect the refining performance. (C) 2009 Elsevier B.V. All rights reserved.