【摘要】 通过光学显微镜和扫描电镜考察了冷却速率及Sr加入量对亚共晶Al-Si合金中共晶Si形貌变化的影响。Boltzman方程对共晶Si变质等级关系曲线拟合结果表明：随着冷却速率提高，共晶Si完全变质所需要的临界Sr量减少，共晶Si的变质等级与Sr的加入量高度相关，相关系数R2大于0.99。可以推断，在正常铸造条件下，存在变质阈值。此外，在低冷却速率和高Sr量的合金中，出现局部变质不良，其原因与Al2Si2Sr形成有关。更多还原

【Abstract】 The effects of cooling rate and Sr addition on the morphology of eutectic Si in hypoeutectic Al-Si alloy were investigated by optical microscope(OM) and scanning electron microscope(SEM) The results of Boltzman equation fitting the relationship curve of eutectic Si modification grade showed that as the cooling rate increased, the critical amount of the Sr required for complete metamorphism of eutectic Si decreased, and the modification grade of the eutectic Si was highly correlated with the amount of the Sr addition. The correlation coefficient R2 was more than 0.99. It can be inferred that there is a modification threshold under normal casting conditions. In addition, in the low-cooling rate and high-Sr content, local modification occurred, and the cause is related to the formation of Al2Si2Sr.更多还原