普通铸造Mg-25Zn-12Ho镁合金的微观组织研究

Investigation on Microstructure of As-cast Mg-25Zn-12Ho Magnesium Alloy

通过光学显微镜、X射线衍射仪、差示扫描量热分析仪、扫描电镜和透射电镜研究了Mg-25Zn-12Ho铸态合金的微观组织。结果表明：试验合金铸态微观组织主要由三种不同类型的中间相构成,分别为骨骼块状二十面体准晶I相、片层状W相以及致密片状Mg7Zn3相。骨骼状准晶I成分为Mg、Zn和Ho,经液相和W相的包晶反应形成于447℃左右。

The microstructure of as-cast Mg-25 Zn-12 Ho alloy was investigated by optical microscopy, X-ray diffraction,differential scanning calorimeter, scanning electron microscopy and transmission electron microscope. The results indicate that as-cast Mg-25 Zn-12 Ho alloy are mainly composed of three types of phases, such as block icosahedral quas-icrystalline I phase, lamellar W phase and dense lamellar Mg_7Zn_3 phase. The composition of I-phase in the alloy is Mg, Zn, and Ho, which forms at about 447 ℃ by peritectic reaction between liquid phase and W phase.