【摘要】 最为人们接受的硅的变质机理是杂质诱发孪晶假说。锶的变质能力强 ,且变质有效期长。锶的孕育期的长短主要与铝硅合金液中磷的含量有关。由于共晶硅中的孪晶密度随硅的生长速度的降低而减少 ,锶变质要求合金冷却速度要高于一定的临界值。磷、锑、铋、钙、稀土等元素对锶的变质有毒化作用。锶变质会导致铸件中孔洞的增加。更多还原

【Abstract】 The tranditional hypothesis on modification of eutectic silicon in Al-Si alloys is that the impurity induces twin-crystal proposed by Shu and Hellawell.Sr modification has features of strong modification ability and long effective modification period.Sr incubative period is mainly relevant to the P concentration in the melt.With Sr modification,the cooling rate of the melt should be higher than a critical value due to decreasing in the twin-crystal density with the decrease of the growth rate of the eutectic silicon.Sr modification can result in the increase of the porosity in the Al-Si castings.Sb,P,Bi,Ca and MM(mistchmetal) have the detriment to the Sr modification.更多还原