Mg-9Al-0.5Zn-0.3Be熔体表面氧化行为

在Mg 9Al 0 .5Zn合金中添加 0 .3%铍 ,镁合金液抗氧化性能得到极大提高 ,可以直接暴露在大气中熔炼。X射线衍射表明 ,合金表面有结构远较氧化镁致密的氧化铍生成 ,从而导致整个氧化膜致密程度提高。利用俄歇电子能谱 (AES)进行氧化膜元素深度剖析发现 ,在含 0 .3%铍的镁合金液表面生成的氧化膜可以分为 3个亚层 :最外层为氧化镁层 ;中间层为致密复合层 ,由氧化铍、氧化镁和氧化铝组成 ;内层为氧化膜向基体的过渡层。热力学分析表明 ,氧化膜中的这种分层结构同镁的高蒸汽压以及自由能变化吻合。

Oxidation behavior of beryllium on Mg-9Al-0.5Zn alloy melt

After adding 0.3% beryllium, the oxidation resistance of the liquid magnesium alloy Mg 9Al 0.5Zn was enhanced greatly and it even can be melted exposing to air. X ray diffraction indicated that beryllium oxide, which was much compacter and tougher than magnesia, formed on the melt surface. AES depth profile analysis showed that the surface oxide film could be divided into three sub layers. The outside layer was mainly made up of magnesia, the middle layer, which consisted of beryllium oxide, magnesia and aluminum oxide, was compound and compact, the inside layer was a transition layer to substrate. Thermodynamic analysis indicated that the structure of the surface oxide film was accordant to the change of free energy and high vapor pressure of magnesium.