旋转磁场对高硅铝合金凝固过程中相组织演变的影响

Influence of rotating magnetic field on evolution of phase structure evolution in high-silicon aluminum alloys

研究旋转磁场的励磁电流和旋转频率对高硅铝合金凝固组织的影响,并利用高速摄像机、SEM和EDS对高硅铝合金中硅相及其他金属间化合物形貌的演变进行分析。结果表明,旋转磁场可以抑制高硅铝合金的宏观偏析,细化初晶硅颗粒,形成类共晶组织;随着励磁电流和旋转频率的增大,初晶硅转变方式为长棒状-块状-大块块状团簇,共晶硅转变方式为长针状-蠕虫状-针状:旋转磁场还可以改善A1_2Cu相和A1-Si-Fe相的形貌,使其依附甚至包覆在Si相周围生长,抑制合金熔体中Si相的长大,有助于改善合金的力学性能。

The influence of excitation current and rotational frequency on the solidification microstructure of high-silicon aluminum alloys was studied. The morphology evolution of Si and other intermetallic compounds was analyzed by using high speed camera, SEM and EDS. The results show that the rotating magnetic field（RMF） can suppress the macrosegregation in solidified high-silicon aluminum alloys, refine the primary Si particles and finally provide a eutectic-like structure. The morphology of primary Si phase changes from long rod to block, and then to large block clusters when both the excitation current and rotational frequency of RMF increase, meanwhile, the eutectic Si phase changes from long needle to wormlike particles, and then to needlelike particles. Moreover, RMF can improve the morphologies of Al 2 Cu and Al-Si-Fe phases, and the refined Al 2 Cu and Al-Si-Fe phases are attached around Si phase, which further refines the microstructure of the high-silicon aluminum alloys.