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为研究液态Al初期氧化产物的相组成及其氧化机理,采用环境透射电镜(E TEM)对纳米Al粉末在720℃时的氧化进行了原位观察.差热分析(DTA)和TEM形貌观察结果表明,纳米Al粉末表面存在5—6nm厚的非晶Al_2O_3膜,该非晶膜在350—550℃间转变为γ-Al_2O_3.纳米Al粉末在10~(-4) Pa高真空下熔化后冷却,可以得到无氧化膜的固态Al.再次熔化后的Al在720℃,10~(-2) Pa氧分压下氧化,直接形成棒状的纳米αAl_2O_3.同时,XRD检测结果表明,熔融的块状金属Al在720℃,10~(-2)Pa氧分压下氧化,也得到αAl_2O_3.液态Al的这种特殊氧化结果与其液态结构以及液态Al蒸发成气体再氧化有关.
In order to study the phase composition and oxidation mechanism of the initial oxidation products of liquid Al, the oxidation of nano-Al powder was observed at 720 ℃ by using environment transmission electron microscope (TEM). Differential thermal analysis (DTA) and TEM observation The results show that there is a 5-6 nm thick amorphous Al 2 O 3 film on the surface of the nano-Al powder and the amorphous film is transformed into γ-Al 2 O 3 at 350-550 ° C. The nano-Al powder melts under high vacuum of 10 -4 Pa And then cooled to obtain the solid Al without oxide film.The remelted Al was oxidized at 720 ℃ and 10 ~ (-2) Pa oxygen partial pressure to form the rod-shaped nano-αAl_2O_3 directly.At the same time, the XRD results showed that the melted lump Al-like metal is oxidized at a partial pressure of 10 ~ (-2) Pa at 720 ℃, and also gives αAl_2O_3. This special oxidation of liquid Al is related to its liquid structure and vaporization of liquid Al to gas reoxidation.