Al-Ti-C-Sr master alloy--A melt inoculant for simultaneous grain refinement and modification of hypoeutectic Al-Si alloys

摘要

Present article is focused on the microstructural features of Al-Ti-C-Sr master alloy, an inoculant for simultaneous grain refinement and modification of hypoeutectic Al-Si alloys. This master alloy is basically a metal matrix composite consisting of TiC and Al_4Sr phases formed in situ in the Al-matrix. TiC particles initiate the refinement of primary alpha-Al through heterogeneous nucleation in molten hypoeutectic Al-Si alloy, while Al_4Sr phase dissolves in molten Al-7Si alloy enriching the melt with Sr, which eventually leads to modification of eutectic silicon during solidification of the Al-7Si alloy casting. Thus present master alloy serves in both ways, as a grain refiner and a modifier for hypoeutectic Al-Si alloys.