稀土元素Ce、Dy、Nd对Mg-Zn-Y基准晶合金显微组织的影响

Effects of RE(RE=Ce,Dy,Nd)on Microstructures of Mg-Zn-Y-based Quasicrystal Alloy

本文在铸铁模具冷却条件下制备了Mg-Zn-Y-RE（RE=Ce，Dy，Nd）准晶合金，并对不同稀土元素对Mg—Zn—Y基准晶合金显微组织的影响进行了研究。结果表明：花瓣状的准晶和层片状的共晶是合金凝固相的主要组成物；EDS分析表明在三种稀土中，Dy更易形成四元准晶，而Nd不易形成四元准晶。进一步的研究表明：四元稀土准晶的形态受球形临界半径的影响，Ce，Dy，Nd三种稀土元素形成球形四元准晶的添加量分别为1．0、0．2、0．5；此外，本文冷却条件下形成四元Mg—Zn—Y—RE准晶的临界半径约为5．5～6．0μm。

Mg-Zn-Y-RE （RE =Ce,Dy,Nd） quasicrystal alloys have been fabricated under cooling conditions of cast iron die. Effects of different RE elements on Mg-Zn-Y-based quasicrystal microstucture have been researched, resulting in that petal-like quasicrystals and lamellar eutectic were main phases. EDS analysis indicated that it was not easy for Nd to form quarternary quasicrystals while it was very easy for Dy to form quarternary quasicrystals. The further study showed that the quarternary quasicrystal morphology was decided by the spherical critical radius. The contents of RE for forming spherical quarternary quasicrytals were 1.0 for Ce, 0.2 for Dy and 0.5 for Nd, respectively. Moreover, the critical stable radius Rr of Mg-Zn-Y- RE quasicrystals was about 5.5-6.0wm under cooling process of this paper.