交流磁场对过共晶Al-Fe合金初生相的影响

Effect of Alternating Current Magnetic Field on the Primary Phase of Hypereutectic Al-Fe Alloy

利用XRD和OM研究了交流磁场对过共晶Al-2.55%Fe合金初生相的影响。结果表明:交流磁场不会改变过共晶Al-2.55%Fe合金初生相的类型,有无交流磁场作用下,初生相均为Al3Fe相,但交流磁场能显著改变初生Al3Fe相的分布和形貌。无磁场条件下,初生Al3Fe相在重力的作用下均匀分布在样品的底部,呈细小颗粒状。而在交流磁场的作用下,除了少部分细小颗粒状的初生Al3Fe相在样品底部呈金字塔状分布外,大部分初生Al3Fe相出现在样品的顶端边沿处,沿径向呈三角形分布。同时,顶部初生Al3Fe的相形貌由原来的细小颗粒状变为大的块状和棒状。随着磁感应强度的增大,交流磁场对初生Al3Fe相分布和形貌的影响增大,顶部初生Al3Fe相的含量增多。交流磁场对过共晶Al-2.55%Fe合金初生相分布和形貌的影响,主要是由交流磁场产生的Lorentz力和磁力共同作用的结果。

The type,morphology and distribution of the Fe-phase in the Al-Fe alloy are some of the key factors affecting the mechanical properties of the Al-Fe alloy.The alternating current(AC)magnetic field can significantly affect the solidification structure of the Al-Fe alloy.However,the mechanism of the Fe-phase in the Al-Fe alloy influenced by the AC magnetic field has not been fully revealed.Therefore,the effect of AC magnetic field on the primary phase of hypereutectic Al-2.55%Fe alloy is studied by means of XRD and OM in this work.The results show that the AC magnetic field cannot change the type of primary phase of the hypereutectic Al-2.55%Fe alloy,which means that the primary phase remains to be Al3 Fe phase regardless of the treatment of the AC magnetic field,but the AC magnetic field can obviously influence the distribution and the morphology of the primary Al3 Fe phase.Without treatment of AC magnetic field,the primary Al3 Fe phase is fine and granular,and uniformly distributed at the bottom of the sample under the effect of gravity.However,under the influence of the AC magnetic field,most of the primary Al3 Fe phase is located at the top edge of the sample and is distributed in the shape of a triangle along the radial direction,with only a small part of the fine,granular primary Al3 Fe phase distributed in the shape of a pyramid at the bottom of the sample.At the same time,the primary Al3 Fe phase morphology in the top of the sample transforms from the original fine particles to large blocks and rods.With the increase of the magnetic induction intensity,the influence of the AC magnetic field on the distribution and morphology of the primary Al3 Fe phase grows stronger,and the content of the primary Al3 Fe phase in the top of the sample also increases.The influence of AC magnetic field on the primary phase distribution and morphology of the hypereutectic Al-2.55%Fe alloy is the result of the combined action of the Lorentz force and the magnetic force generated by the AC magnetic field.