Refinement of hypereutectic Al–Si alloy by a new Al–Zr–P master alloy

In this article, a novel Al–6Zr–2P master alloy with ZrP particles was successfully synthesized. Field-emission scanning electron microscope (FESEM) observation on the phases extracted from the master alloy showed flaky ZrAl3 phase adheres to the ZrP particles, indicating ZrP phase would precipitate firstly in the solidification process and then the ZrAl3 phase attaches to the pre-formed ZrP particles and grows. The reason for the excellent refining performance of Al–6Zr–2P master alloy was that Si clusters could promote the transformation of ZrP to AlP and subsequently AlP acts as the heterogeneous nucleation sites of primary Si phase.