Vol.20 No.3 毛卫民等：凝固条件对ASMg合金半固态加热时组织的影响 *257 证明：在597℃的重熔温度下，电磁搅拌对AISi,Mg合金半固态重熔时α相的球化也具有重 大影响，仅对枝晶组织加以细化的措施无法使AISi,Mg合金半固态重熔时的：相获得完全的 球化 3.结论 经过电磁搅拌的A1Si,Mg合金，在589℃或597℃下半固态加热保温，在较短的时间内 (5~10min),即可获得球团状a相的半固态组织；而细小枝晶的A1Si,Mg合金，在同样的加热 温度下，即使保温60mim,也无法获得完全球状a相的半固态组织.经过电磁搅拌的A1Si,Mg 合金在半固态重熔时，α相能够快速球化的主要原因是，搅拌破碎了粗大的枝品，促使二次枝 晶臂的缩颈、熔断， 参考文献 I Spencer D B.Mehrabian R.Flemings M C.Rheological Behaviour of Sn-15%Pb in the Crystal- lization Range.Metall Trans,1972.3A:1925 2 Flemings M C.Behaviour of Metal Alloy in the Semi-solid State.Metall Trans,1991,22A:957 3 Hint G.Zillgen M,Cremer R.et al.Recent Advances in Thixoforming to Produce Near Net shape Compo. nents.In:Proceedings of the First China International Die Casting Congress.Beijing,China,1997.259 4 Brown S B.Flemings MC.Nel-shpe Forging via Semi-solid Processing.Adv Mater Process,1993.143:36 5 Young K P,Fitze R.Semi-solid Metal Cast Aluminium Automotive Components.In:The 3rd Int Conf of Semi-Solid Processing of Alloys and Compositions.Tokyo:University of Tokyo.1994 Effect of the Solidification Conditions on the Microstructures of AlSi,Mg Alloy during Semi-solid Remelting Mao Weimin Zhong Xueyou Material Science and Engineering School,UST Beijing,Beijing 100083,China ABSTRACTS The effect of the solidification conditions on the microstructures was stud- ied during partial remelting of AlSi,Mg alloy with the help of an electrical pipe-type fumace.The results show that the eutectic is remelted above all and a phases are gradu- ally evolved into spheroidal shape,if the AlSi,Mg alloys stirred strongly by rotating electro- magnetic field during the first solidification are heated again to 589c or 597C and have been held for a short time(for example,5~10 min),and moreover,the higher the holding temperature,the faster the eutectic remelting process and a phase's evolution are.In contrast, even though the AlSi,Mg alloy's samples non-stirred with fine dendritic microstructures are heated to the same temperatures as those stirred by rotating electromagnetic field and have been held for 60 min,it is not possible to change all the dendritic a phases to sper- oidal a phase. KEY WORDS AlSi.Mg:remelting:electromagnetic stirring;dendrite