EFFECT OF MICROSTRUCTURAL VARIATION ON MECHANICAL PROPERTIES OF HYPEREUTECTIC Al-Si CASTING ALLOYS

摘要

The effects of the addition of phosphorus and the spheroidization of primary silicon particles on mechanical properties such as tensile strength and both static and impact fracture toughness were investigated in hypereutectic Al-Si casting alloys with several silicon concentration. The mechanical properties decrease with increasing silicon concentration. Minute primary silicon particles with round corners are obtained by applying modification, and they are spheroidized by adding spheroidization treatment. The modification by adding phosphorus contributes to the improvement in mechanical properties. The spheroidized alloys exhibit more obvious improvement, except for the static fracture toughness.