旋转磁场对Al-7Si-8.9Mg_2Si复合材料凝固组织的影响

Effects of Rotating Magnetic Field on Microstructure of Al-7Si-8.9Mg_2Si Composite

通过微观组织分析研究了在旋转磁场作用下Al-7Si-8.9Mg2Si复合材料的凝固组织特征。结果表明,合金凝固组织经过电磁搅拌后初生Mg2Si相明显细化,仅在近液态和半固态施加旋转磁场使得二元共晶Mg2Si的形状变化很小,在凝固全程施加旋转磁场反而使得组织粗化。在半固态施加旋转磁场能有效细化Al-7Si-8.9Mg2Si复合材料凝固组织中初生Mg2Si和共晶Mg2Si相,并使得α-Al相变得细小且非枝晶化。

The effects of rotating magnetic field on the microstmcture of A1-7Si-8.9Mg2Si composite were studied by optical microscope. The results show that primary Mg2Si phase appearance becomes smaller after magnetic field rotating. When the rotating magnetic field with proper parameter is applied in the liquid and solidification of AI-7Si-8.9Mg2Si composite, the morphology and size of eutectic Mg2Si phases improves little. If the rotating magnetic field is applied in whole process from liquid to solid, the eutectic Mg2Si phase coarsens contrarily. When the rotating magnetic field with proper parameter is applied in semi-solid melt of AI-7Si-8.9Mg2Si composite, Mg2Si and ct-Al phases are effectively refined and become small and non-dendrite.