中文摘要：

通过常规凝固方法在Mg28Zn2Y三元合金中的富Mg区获得了二十面体稳定准晶相。Mg28Zn2Y三元合金铸态组织中存在α-Mg相，Mg7Zn3相和二十面体准晶相。该合金的准晶形貌有两种：一种为尺寸较大、具有五次对称性的花瓣状；另一种为尺寸稍小、对称性不太明显的团状。五次对称性的花瓣状形貌是二十面体准晶，是按其特有的五次对称轴的择优方向自由生长所致。冷却速率直接影响合金凝固过程中准晶熟化时间。熟化时间越长，越容易使准晶花瓣端部粗化以及在端部发生分又。端部的分叉容易使得花瓣准晶破碎，破碎的准晶游离到低温相中，在界面能的作用下形成多边形形貌。

英文摘要：

Applying XRD, OM, SEM and TEM techniques, an investigation on the solidification of Mg28Zn2Y quasicrystal alloy was carried out. It is found that α-Mg phase, Mg7Zn3 phase and icosahedral quasicrystal phase coexist in the as-solidified morphology. A perfect five-branch icosahedral quasicrystal morphology was observed. It is attributed to the icosahedral quasicrystal free growth with preferred growth direction of five-fold symmetry axes resulting in five-branch morphology. Furthermore, the effect of cooling rate on the quasi-crystal morphology was also studied. High cooling rate leads to rapid solidification, and in turn, petal-like quasi-crystal morphology is reserved. On the other hand, slow cooling rate favors coarsening and branching of the quasi-crystal, and subsequently, subjected to long curing time, the formation of polygonal quasi-crystals driven by the action of interface energy.