(上海交通大學(xué) 材料科學(xué)與工程學(xué)院， 上海 200030)
摘 要: 在Mg9Al0.5Zn合金中添加0.3%鈹， 鎂合金液抗氧化性能得到極大提高， 可以直接暴露在大氣中熔煉。 X射線衍射表明，合金表面有結(jié)構(gòu)遠(yuǎn)較氧化鎂致密的氧化鈹生成， 從而導(dǎo)致整個(gè)氧化膜致密程度提高。 利用俄歇電子能譜(AES)進(jìn)行氧化膜元素深度剖析發(fā)現(xiàn)，在含0.3%鈹?shù)逆V合金液表面生成的氧化膜可以分為3個(gè)亞層： 最外層為氧化鎂層；中間層為致密復(fù)合層， 由氧化鈹、氧化鎂和氧化鋁組成； 內(nèi)層為氧化膜向基體的過渡層。 熱力學(xué)分析表明， 氧化膜中的這種分層結(jié)構(gòu)同鎂的高蒸汽壓以及自由能變化吻合。
關(guān)鍵字: 氧化膜； 鈹； 鎂合金； 自由能
（School of Materials Science and Engineering，Shanghai Jiaotong University, Shanghai 200030, P.R.China）
Abstract:After adding 0.3% beryllium, the oxidation resistance of the liquid magnesium alloy Mg9Al 0.5Zn was enhanced greatly and it even can be melted exposingto air. Xray diffraction indicated that beryllium oxide, which was much compacter and tougherthan magnesia, formed on the melt surface. AES depth profile analysis showed that the surface oxide film could be divided into three sublayers. 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.
Key words: oxide film； beryllium； magnesium alloy
