脉冲磁场对AZ91D镁合金凝固组织的影响

Effect of Pulsed Magnetic Field on Solidified Structure of AZ91D Magnesium Alloy

研究了脉冲磁场作用下AZ91D镁合金凝固组织的变化,考察了冷却速度、磁场强度和放电频率对AZ91D镁合金晶粒大小的影响,并对磁场影响凝固组织的机理进行了探讨。试验结果表明:在脉冲磁场的作用下,AZ91D镁合金的凝固组织显著细化,其初生相由发达的树枝晶转变为均匀细小的蔷薇状晶体,共晶网络变得细小且不连续,聚集在晶界上的共晶组织减少;合金的晶粒尺寸随着冷却速度的降低,磁场强度或放电频率的增加而逐渐减小。

The influences of cooling rate, magnetic density and discharging frequency on the solidified structure of magnesium alloy AZ91D under pulsed magnetic field were studied, and the related mechanism was also discussed. Under the pulsed magnetic field, solidified structure of AZ91D magnesium alloy is refined greatly. The dendrite morphology of the primary phase is changed and the rosettes primary a-Mg phase formed. The network of eutectic phase is discontinuous and the amount of eutectic phase distributed on grain boundary decreases. With the decrease of cooling rate of melt, the increase of magnetic density or discharging frequency, the grains size of magnesium alloy AZ91D decreases.