Effect of microstructure on the mechanical properties and fracture of commercial hypoeutectic Al-Si alloy modified with Na, Sb and Sr

摘要

The microstructure, hardness, tensile properties andfracture have been studied for the non-modified and modifiedaluminium (Al) silicon (Si) commercial hypoeutectic alloy. Threemodifiers were used being sodium (Na), antimony (Sb) andstrontium (Sr). The Sb-modified structure revealed small plate-likeSi morphology. The Na and Sr-modified structures exhibitedfibrous Si. A slight increase in the hardness values (HV) due tomodification was observed. A general increase in the tensileproperties was observed due to modification. The tensileproperties of the sand mould Sr-modified alloy were significantlyhigher than those of the Na-modified alloy by 12.7% in proofstress, 16.3% in ductility and 33.3% in toughness. For the metalmould ingots the increase in tensile properties of Sr-modified alloywere respectively: 16.7%, 32.5% and 41.7% compared to a Na-modified alloy.