采用扩渗法在镁合金表面共渗Al-Zn,研究了扩渗时间和温度对表面合金层显微组织的影响.结果表明:当温度为390%时,随着扩渗时间的增加,生成的表面合金层由不连续金属间化合物层(Al6Mg10Zn、Al5Mg11Zn4)+过渡层变为连续金属间化合物层+过渡层;此过程应是物理置换扩散机制和反应扩散机制同时存在,生成的金属间化合物相主要为Al6Mg10Zn和Al5Mg11Zn4两种类型金属间化合物,其中Al5Mg11Zn4是较为稳定的相;当温度提高到410℃时,晶界扩散活性提高,晶界扩散通道增强,仅为2小时已出现了严重的沿晶界扩渗,造成合金层中金属间化合物沿晶界呈网状不均匀分布.
An Al-Zn alloyed surface layer on magnesium alloy was prepared by a co-aluminizing-zicizing process with Al and Zn powders. The effect of processing time and temperature on the microstructure of surface alloyed layer was studied. The result showed that with the time increase from 2 h to 6h at 390℃, the formed surface alloyed zone seemed to be consisted of discontinuous islets of intermetallic compounds (Al6Mg10Zn and Al5Mg11Zn4+transition layer, and then transformed to ones consisted of continuous in-termetallic compound layer+transition layer. The intermetallic compounds formed in the alloyed layer are Al6Mg10Zn and Al5Mg11Zn4 ,the latter being much stable. When the temperature increases to 410℃, serious grain boundary diffusion started by 2 h, when a network like microstructure of intermetallics ap-peared along grain boundary in the front of the alloyed layer.
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