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利用旋转磁场控制Mg15Al二元高铝镁合金凝固过程,以期获得均匀细小的等轴晶,使合金后续的等通道挤压能顺利进行。通过OM、SEM、EDS测试手段研究了旋转磁场对合金凝固组织及溶质分配的影响。结果表明:旋转磁场主要通过与金属液流相互作用引起强烈的旋流而产生搅拌作用来影响合金的温度场与溶质场的分布,故能够显著细化Mg15Al二元高铝镁合金组织中的初晶α-Mg,促进Al在初晶α-Mg中的固溶,但对于在凝固末期才形成的共晶组织而言,由于凝固末期所剩液相形不成有效流动,其形态受旋转磁场影响不大。随励磁电压增大,晶粒细化效果增加,励磁电压为60V时,晶粒细化效果最佳,Al在初晶α-Mg中固溶量最高,励磁电压继续增加,由于磁场感生热增加将弱化二次冷却,使晶粒细化效果下降。
The rotating magnetic field is used to control the solidification process of Mg15Al binary high-aluminum-magnesium alloy in order to obtain uniform and fine equiaxed grains so that the subsequent equal-channel extrusion of the alloy can be carried out smoothly. The effects of rotating magnetic field on the solidification structure and solute distribution were investigated by OM, SEM and EDS. The results show that the rotating magnetic field mainly influences the distribution of the temperature field and the solute field in the Mg15Al binary high-aluminum-magnesium alloy by the strong swirling caused by the interaction with the metal flow and the stirring effect. Crystal α-Mg, which promotes the solution of Al in primary α-Mg. However, the eutectic microstructure formed at the end of solidification can not be effectively flowed because of the liquid phase at the end of solidification. Its morphology is affected by rotational magnetic field Not big. With the increase of excitation voltage, the effect of grain refinement increases. When the excitation voltage is 60V, the grain refinement effect is the best. Al is the highest in the primary crystal α-Mg, and the excitation voltage continues to increase. Increase will weaken the secondary cooling, the grain refinement effect decreased.