| 熔态镁合金在空气/SF_6保护气氛中形成的膜特征 | |
| 聂书红 ; 胡泊 ; 熊守美 ; 柳百成 ; NIE Shu-hong ; HU-Bo ; XIONG Shou-mei ; LIU Bai-cheng | |
| 2010-06-08 ; 2010-06-08 | |
| 关键词 | 表面膜 镁合金 熔炼 空气/SF6保护气体 surface film magnesium alloy melting air/ SF_6 protective gas TG174.4 |
| 其他题名 | Characterization of Protective Surface Films on Molten AZ91D Magnesium Alloy Formed in Air and SF_6 Protective Gas |
| 中文摘要 | 镁及其合金的铸造、熔炼需要在SF6的保护气氛中进行,目前对其研究还不完善。为此,用SEM,TEM和XRD研究了熔态AZ91D镁合金在空气/SF6保护气氛中形成的表面膜特征。结果表明:保护性表面膜分为两层,最外层主要为疏松多晶的MgO及含有少量Al的氧化物和微量的氟化物;内层为结晶MgF2;随着AZ91D在保护气氛中暴露时间的增加,表面膜中F/O原子比显著增加,表面粗糙度增加;表面膜超过一定厚度后,主要为F和Mg发生反应;表面膜表面弥散着大小不一的白色片状物,其主要成分为MgO,内含少量MgF2。部分近表面区域断面中有不连续的白亮富F(原子分数约为70%)小半圆区域,富F的小半圆亮区之间F含量显著降低;部分为一条厚度不均匀的白亮带,其中F原子分数也很不均匀。富F区中F/Mg原子比显著大于MgF2中的2/1,F可能通过富F区域不断从保护气氛向AZ91D镁合金内部扩散形成MgF2。; With a view to the fact that the casting and melting of magnesium and its alloy are generally carried out in the protective gas SF_6, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction were used to analyze the characteristics of the surface film on AZ91D magnesium alloy molten in air/SF_6 protective gas. It was found that the protective surface film was composed of two layers. Namely, the upper layer was composed of a large amount of loose polycrystalline MgO, a little amount of aluminum oxide, and trace fluoride; and the inner layer was composed of crystalline MgF_2. The atomic ratio of F/O in the surface film increased evidently and so did the surface roughness with increasing exposure time. The reaction between magnesium and fluorine was dominant as the film thickness exceeded a certain value. Moreover, some white flakes composed of MgO and a little amount of MgF_2, with varied size and disperse distribution, existed on the film surface. There existed semicircular discontinuous F-rich white spots composed of about 70% fluorine in some near surface zones, and the F content in the area excluding the white spots was greatly reduced. Since the atomic ratio of F/Mg in the F-rich area was higher than 2/1, that of MgF_2, it could be supposed that the fluorine might diffuse from the protective atmosphere to the bulk melt of AZ91D magnesium alloy through the F-rich zone.; 博士后基金资助项目(2004035319) |
| 语种 | 中文 ; 中文 |
| 内容类型 | 期刊论文 |
| 源URL | [http://hdl.handle.net/123456789/47752]  |
| 专题 | 清华大学 |
| 推荐引用方式 GB/T 7714 | 聂书红,胡泊,熊守美,等. 熔态镁合金在空气/SF_6保护气氛中形成的膜特征[J],2010, 2010. |
| APA | 聂书红.,胡泊.,熊守美.,柳百成.,NIE Shu-hong.,...&LIU Bai-cheng.(2010).熔态镁合金在空气/SF_6保护气氛中形成的膜特征.. |
| MLA | 聂书红,et al."熔态镁合金在空气/SF_6保护气氛中形成的膜特征".(2010). |
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