电磁搅拌与变质复合作用对Al-20Si合金初生硅相的影响

使用电磁搅拌、变质处理及其复合工艺分别成功制备了过共晶Al-20Si半固态浆料，研究了电磁搅拌和变质的复合作用对过共晶Al-20Si合金中初生Si长大和形貌的影响。研究结果表明：复合作用可以获得比单种变质处理和电磁搅拌的过共晶Al-20Si合金更加细小、更加圆整的初生Si组织。复合作用获得的初生硅比单一处理尺寸平均减小25．19％，圆整度平均提高8．40％。而且共晶Si组织也得到球化。复合作用细化组织的机理为：变质后施加旋转磁场，促进了变质剂的扩散，更多的初生Si与共晶Si组织相互打碎，深化了变质和电磁搅拌效果，细化显微组织。

Combined Effects of Electromagnetic Stirring and Modification on Primary Si in Hypereutectic Al-20Si Alloy

The semi-solid hypereutectic Al-20Si alloys have been prepared by electromagnetic stirring,modification and combination action,respectively.The effects of combination action of electromagnetic stirring and modification on growth and morphology of primary Si in hypereutectic Al-20Si alloy were observed.The results show that compared with that of by modification and electromagnetic stirring,the microstructure of primary Si in hypereutectic Al-20Si alloy prepared by combination means is finer and more roundness,decreased by 25.19$$$$ % in average grain size and increased by 8.40$$$$ % in average roundness,meanwhile,microstructure of eutectic Si can be spheroidized.The mechanism of combination refinement is revealed that applied rotating magnetic field after modification has promoted the diffusion of modifier to make the mutual destruct between more primary Si and eutectic Si structure,enhancing the effects of modification and electromagnetic stirring and refining microstructure.