Microstructure of Al-17wt.%Si Alloy after Overheating and CuP Master Alloy Modification

In the dissertation the influence of overheating of around 250°C above Tliq and modification with phosphorus (CuP10 master alloy) on the microstructure of AlSi17Cu5 cast alloy has been shown. Substantial overheating above Tliq temperature of the alloy, causes complete dissolving of the β (Si) phase. In the liquid alloy, multiple areas are being created of different dissolved silicon content, where, as in the result of the overheating, the homogeneous nucleuses are being partially created. After modification with phosphorus, in liquid alloy, additional heterogenic nucleuses (AlP) of primary silicon crystals are being created. In the close neighborhood of these micro-areas, places depleted of silicon appears, where pre-eutectic α (Al, Me) dendrites crystallize.