钇对铸态ZK60镁合金晶界析出相形态的影响

通过金相分析、扫描电镜(SEM)以及能谱(EDX)分析等实验手段,对Mg-6.0Zn-0.45Zr,Mg-6.0Zn-1.2Y和Mg-6.0Zn-0.6Zr-1.0Y三种合金铸态晶界析出相的形态进行了研究.实验结果表明,铸态Mg-6.0Zn-0.45Zr合金的晶界主要析出相是Mg-Zn二元相. 铸态Mg-6.0Zn-1.2Y合金与Mg-6.0Zn-0.6Zr-1.0Y合金的晶界析出相相似,主要以两种形态出现,一是在三角晶界形核,呈"鱼骨状",由Mg-Zn二元相和Mg-Zn-Y三元相组成;另一是几乎包围整个晶粒,呈连续网状,由Mg-Zn-Y三元相组成.另外,在含Y的合金中还发现,晶界析出相的边缘均有大量弥散的颗粒状析出物,颗粒呈辐射状向晶粒内部延伸分布.Y能强烈改变铸态Mg-Zn-Zr系合金(ZK60)的晶界析出相的形态.

Effect of Yttrium on Morphologies of Precipitation Phases Along Grain Boundary of As-cast ZK60 Magnesium Alloy

Morphologies of precipitation phases along grain boundary of the as-cast Mg-6.0Zn-0.45Zr, Mg-6.0Zn-(1.2Y) and Mg-6.0Zn-0.6Zr-1.0Y alloys are studied by using the methodologies of metallurgical phase analysis, scanning electron microscopy(SEM) analysis and energy diffraction x-ray(EDX) analysis. The experimental result indicates that the main precipitation phases along grain boundary of the as-cast alloys Mg-6.0Zn-0.45Zr is Mg-Zn binary phase. There are two kinds of precipitation phases along grain boundary for Mg-6.0Zn-1.2Y and Mg-6.0Zn-(0.6)Zr-1.0Y alloys. One grew at triangular grain boundary, which is fish-bone -like and contained Mg-Zn binary phase and Mg-Zn-Y ternary phase. The other distributed mainly around the grain, which is net-like and contained Mg-Zn-Y ternary phase. In addition, there are lots of granular phases, extending to the interior of the grain, at the rim of grain boundary phases. Finally, Y can intensively change morphology of precipitation phases along grain boundary of the as-cast Mg-Zn-Zr alloy (ZK60) alloys.