强磁场下电磁振荡对Al-Si过共晶合金凝固中初生硅分布和形貌的影响

EFFECTS OF ELECTROMAGNETIC VIBRATION ON THE DISTRIBUTION AND MORPHOLOGY OF PRIMARY SILICON IN Al-Si HYPEREUTECTIC ALLOY SOLIDIFIED UNDER HIGH MAGNETIC FIELDS

研究了强磁场与交变电流复合作用产生的振荡对Al-18%Si合金中初生硅分布和形貌的影响规律.结果表明,磁场强度较小时,初生硅发生偏聚现象;随着磁场强度的增大(10T),初生硅的偏聚现象逐渐减小至消失,并且随着振荡力的增大,初生硅由星瓣状向板条状和近颗粒状转变.同时,分析了初生硅的迁移行为,发现磁场下颗粒迁移的终端速度随颗粒尺寸的减小以及磁场强度的增大而降低.理论分析与实验结果相符.

The effects of electromagnetic vibration on the distribution and morphology of primary silicon in the Al-18%Si alloy have been investigated systematically. The experimental results show that the primary silicon agglomerated and was expelled to the top of the sample when the magnetic intensity is low. The segregation of silicon grains decreased gradually and the agglomerating phenomenon disappeared with the increase of magnetic intensity （10 T）, and the coarse star-like primary silicon turned refined flake or square morphologies. It is shown that the migration of primary silicon is depended on gravity and the effective viscous force caused by the magnetic field, and the terminal migration velocity is proportional to the radium of primary silicon and inversely to the intensity of magnetic field. The observed results are approximately agreed with the theoretical analysis.