电磁搅拌对过共晶Al-Si合金初生Si长大过程和形貌的影响  

Effect of electromagnetic stirring on growth and morphology of primary silicon crystals of hypereutectic Al-Si alloys

作　　者：毛卫民[1] 李树索[1] 赵爱民[1] 崔成林[1] 钟雪友[1] 

机构地区：[1]北京科技大学铸造研究所,北京100083

出　　处：《材料科学与工艺》2001年第2期117-121,共5页Materials Science and Technology

基　　金：国家自然科学基金资助项目 !(5 97710 11)

摘　　要：研究了电磁搅拌对过共晶Al -Si合金中初生Si长大和形貌的影响 .结果表明 :当合金含Si量低于30 %时 ,电磁搅拌引起过共晶Al-Si合金中初生Si显著细化和球团化 ,但当合金含Si量超过 30 %时 ,电磁搅拌对初生Si细化的作用有限 ,组织中仍然存在较粗大的板片状初生Si;提高电磁搅拌时合金熔体冷却速度可减小初生Si的尺寸 ;进行正、反转电磁搅拌 ,初生Si的尺寸将进一步减小 .在电磁搅拌条件下 ,初生Si发生细化和球团化的主要原因是 :搅拌引起合金熔体温度场、溶质场的均匀化 ,引起初生Si的机械破碎。The effect of electromagnetic stirring on growth and the morphology of primary silicon crystals in hypereutectic Al-Si alloys during solidification has been studied systematically in this paper.The experimental results show that when the silicon content is equal to or lower than 30%, the primary silicon crystals can be refined significantly and their nodular shape can be obtained by electromagnetic stirring. When the silicon content is more than 30%, however, the refinement of primary silicon crystals is limited and there are still some large lamellar primary silicon crystals in the microstructure. When the cooling rate of the melt during electromagnetic stirring is increased, the grain size of the primary silicon crystals can be reduced. The grain size of the primary silicon crystals can be further decreased by the electromagnetic stirring with positive and reverse runnings. In case of electromagnetic stirring, the main reasons for the refining and nodulizing of primary silicon crystals are: homogenization of temperature and solute fields, the mechanical brokening of silicon crystals and mutual friction among the crystals which restrains the anisotropic growth of the later.

关 键 词：电磁搅拌 过共晶铝硅合金 形貌 初生硅 长大过程 尺寸 细化 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG113.1[金属学及工艺—金属材料]