Effect of alternating magnetic fields on hot tearing susceptibility of Mg–4Zn–1.5Ca alloy

In the present work, the effect of low-frequency alternating magnetic fields (AMFs) of different strengths on hot tearing susceptibility (HTS) and solidification behaviour of the Mg–4Zn–1.5Ca alloy was investigated. The results revealed that the application of AMFs during the solidification narrowed the solidification temperature range of the Mg–4Zn–1.5Ca alloy, thereby reducing the HTS of the material. In addition, the presence of the AMF-inhibited dendritic growth refined the alloy microstructure and enhanced convection in the melt, which led to a decrease in the HTS. The HTS of the Mg–4Zn–1.5Ca alloy was the smallest when the AMF of 15 A (15 Hz) was applied. However, once the current increased to 20 A, excessive Joule heat was generated in the melt, which coarsened the microstructure and increased the HTS of the alloy.