ABSTRACT
The microstructure of an unmodified hypoeutectic Al–Si alloy comprises large primary alpha phase and eutectic alpha phase dendrites and eutectic beta phase crystals. The mechanical properties of silumins can be improved through chemical modification. This article discusses the modification of an EN AC-AlSi10Mg hypoeutectic alloy with the use of a modifier made of processed alloys and an Al–Si alloy solidified at the velocity of 373, 473, 573, and 673 K/s. The applied alloys were referred to as homogeneous modifiers. The content of modifiers in the silumin alloy reached 0.3%–1.5% by weight. The alloy was subjected to tensile strength, relative elongation, and hardness tests before and after modification. The alloy was cast into a sand mold. The results of the study indicate that alloy microstructure can be modified and its mechanical properties can be improved by incorporating the proposed homogeneous modifiers into a liquid alloy. Mechanical properties were improved when an Al–Si modifier with higher silicon content than the modified alloy was used and when the cooling rate was increased to 573 K/s. A further increase in the cooling rate of the modifier did not lead to a significant improvement in the mechanical properties.
