1. College of Science, Northeastern University, Shenyang 110819, China 2. Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110819, China
Cite this article:
ZHANG Jianfeng,LAN Qing,GUO Ruizhen,LE Qichi. Effect of Alternating Current Magnetic Field on the Primary Phase of Hypereutectic Al-Fe Alloy. Acta Metall Sin, 2019, 55(11): 1388-1394.
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 Al3Fe 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 Al3Fe phase. Without treatment of AC magnetic field, the primary Al3Fe 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 Al3Fe 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 Al3Fe phase distributed in the shape of a pyramid at the bottom of the sample. At the same time, the primary Al3Fe 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 Al3Fe phase grows stronger, and the content of the primary Al3Fe 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.
Fig.2 Solidification microstructure of Al-2.55%Fe alloy without alternating current magnetic field (a) and high magnified OM images of zone b (b), zone c (c), zone d (d) and zone e (e) in Fig.2a
Fig.3 Solidification microstructure of Al-2.55%Fe alloy with alternating current magnetic field (20 Hz, 300 A) (a) and high magnified OM images of zone b (b), zone c (c), zone d (d) and zone e (e) in Fig.3a
Fig.4 Solidification microstructure of Al-2.55%Fe alloy with alternating current magnetic field (20 Hz, 200 A) (a) and high magnified OM images of zone b (b), zone c (c), zone d (d) and zone e (e) in Fig.4a
Fig.5 Solidification microstructure of Al-2.55%Fe alloy with alternating current magnetic field (20 Hz, 100 A) (a) and high magnified OM images of zone b (b), zone c (c), zone d (d) and zone e (e) in Fig.5a
Fig.6 XRD spectra of the hypereutectic Al-2.55%Fe alloy with (a) and without (b) alternating current magnetic field (20 Hz, 100 A)
Fig.7 Schematics of the Lorentz force (B—magnetic induction, —permeability of vacuum, —nabla operator)(a) rotational force part (fro) (b) non-rotational force part (fir)
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