中文摘要：

在Mg-Gd-Y-Zr合金凝固过程中施加不同频率的脉冲磁场，研究脉冲磁场对Mg-Gd-Y-Zr合金凝固的影响。实验结果表明，脉冲磁场使Mi-Gd-Y-Zr合金晶粒细化，在频率为5Hz条件下获得最佳的晶粒细化效果，平均晶粒尺寸从未加脉冲磁场条件下的65μm细化到37μm。脉冲磁场的搅拌导致熔体磁过冷及熔体温度梯度降低是晶粒细化的主要原因。脉冲磁场的施加使抗拉强度和延伸率较常规铸造合金分别提高了4．8％、78．5％。

英文摘要：

The effect of the frequency of the pulsed magnetic field on Mg-Gd-Y-Zr alloy during solidification was investigated. When the pulsed magnetic field is applied to Mg-Gd-Y-Zr alloy during the solidification process, the grain refinement is achieved. The average grain size of the as-cast Mg-Gd-Y-Zr alloy is from 65 μm without the pulsed magnetic filed to 37 μm with the pulsed magnetic field of 5 Hz. Grain refinement of Mg-Gd-Y-Zr alloy is due to the electromagnetic undercooling and reduction of temperature gradient by the vibration of melt resulted from the pulsed magnetic field. Compared those casting method with traditional one, the tensile strength and elongation are increased by 4.8% and 78.5%, respectively.