Mn、Fe对AZ91D镁合金中Al_4C_3细化效率的影响

Effect of Mn and Fe on the Grain Refinement Efficiency of AZ91D Magnesium Alloys Refined by Al_4C_3

采用OM、SEM、EDS等测试手段研究了Mn、Fe对Al4C3细化AZ91D镁合金显微组织的影响。结果表明,经0.6%Al4C3细化后,基体合金的平均晶粒尺寸由360μm减小至215μm。在此基础上,将基体合金的Mn含量由0.23%增至0.5%,可使合金的平均晶粒尺寸进一步降至130μm。继续增加Mn量至0.7%时,其晶粒尺寸变化不大。当基体合金中Fe含量由0.0021%增至0.1%时,晶粒尺寸由215μm减小至123μm。Mn、Fe对AZ91D合金中Al4C3细化效率的影响机制可能是,三者共同作用形成的Al-C-O-Mn-Fe复杂颗粒可作为α-Mg晶粒的异质核心。

The effect of Mn and Fe on the grain refinement of AZ91D magnesium alloy refined by Al4C3 has been investigated using OM, SEM and EDS. The results showed that after addition of 0.6%Al4C3,the average grain size of AZ91D base alloy was decreased dramatically from 360μm to 215μm. When the content of Mn increased from 0.23wt% to 0.5wt%, the average grain size was further reduced to 130μm. Adding Mn upto 0.7%, no further refinement of grain size was achieved. When the content of Fe increased from 0.0021% to 0.1%, the average grain size was obviously refined from 2151Jm to 123pm. The mechanism of grain refinement by Mn and Fe was ascribed to the Al-C-O-Mn-Fe particles which may act as heterogeneous crystal nucleus of primary α-Mg.