A356合金熔体中Al2O3夹杂对变质剂Sr的影响

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葛学元, 李建国, 谭红艳, 何迁

( 清华大学材料科学与工程系, 北京100084)

摘要: 通过XRD、SEM等分析手段研究了A356合金熔体中Al2O3夹杂与变质剂Sr之间所发生的反应及其反应机制, 结果发现Sr可以与Al2O3经过一系列反应生成Sr-Al-O化合物, 由此造成了Sr的损耗, 生成的Sr-Al-O化合物可溶于水。在Al-Si合金熔体中加入Sr后, 游离态的Sr与Si会首先生成SrSi2, 而后在熔体中发生三元共晶反应, 生成的Al2Si2Sr化合物呈块状或条状分布。研究还发现存在Al-Si-O化合物, 它覆在Al2Si2Sr化合物表面。

关键词: A356合金; Al2O3; Sr; Sr-Al-O化合物; Al2Si2Sr化合物

中图分类号: TQ175.71; TQ133.1 文献标识码: A 文章编号: 1001- 4977 ( 2008) 01- 0049- 04

Influence of Alumina on Modifier Strontium in A356 Alloy Melt

GE Xue-yuan, LI J ian-guo, TAN Hong-yan, HE Qian

( Department of Materials Science and Engineering, Ts inghua Univers ity, Beijing 100084, China)

Abs tract: The mechanism of the reactions between alumina and modifier s trontium in A356 alloy melt have been inves tigated, by means of XRD and SEM. The results showed that there have been a series of reactions between them, forming the kind of compounds Sr-Al-O, which are water-soluble, and this led to the consumption of s trontium. When adding s trontium into the molten Al-Si alloys , the SrSi2 would form firs tly, and then the Al2Si2Sr compound formed through ternary eutectic reaction, which appeared in the shape of both bulk and s trip. The Al-Si-O compound was also found which laid over the Al2Si2Sr compound.

Key words : A356 alloy; alumina; Sr; Sr-Al-O compounds ; Al2Si2Sr compounds