Un-Uniformity of Eutectic Structure in Al-Si Alloy Modified with Antimony

Dong Guangming1; Liao Hengcheng2; Sun Guoxiong2; Han Zhengtong1

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Un-Uniformity of Eutectic Structure in Al-Si Alloy Modified with Antimony
Vol. 31, Issue 5, Pages: 418-420(2011)
Published： 2011 ，
DOI：

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[1]董光明,廖恒成,孙国雄,韩正铜.Sb变质后Al-Si合金共晶组织的不均匀性[J].特种铸造及有色合金,2011,31(05):418-420+387.

Dong Guangming1, Liao Hengcheng2, Sun Guoxiong2, et al. Un-Uniformity of Eutectic Structure in Al-Si Alloy Modified with Antimony. [J]. Special Casting & Nonferrous Alloys 31(5):418-420(2011)
[1]董光明,廖恒成,孙国雄,韩正铜.Sb变质后Al-Si合金共晶组织的不均匀性[J].特种铸造及有色合金,2011,31(05):418-420+387. DOI：

Dong Guangming1, Liao Hengcheng2, Sun Guoxiong2, et al. Un-Uniformity of Eutectic Structure in Al-Si Alloy Modified with Antimony. [J]. Special Casting & Nonferrous Alloys 31(5):418-420(2011) DOI：

摘要

为了研究Sb变质的Al-13Si-0.4Mg合金中共晶组织的不均匀性

采用液淬技术及光学显微镜考察Sb变质的Al-13Si-0.4Mg合金凝固过程中的组织形成过程。结果发现

在共晶反应初期

先期形成的共晶团的分枝很少

此时形成的共晶组织往往较粗大

表现为共晶Si片较厚、片间距大、分枝少;而此后的共晶反应过程中

共晶团的分枝增加

形成的共晶组织较细小

表现为共晶Si片较薄、片间距小、分枝密集。组织不均匀性的主要原因是Sb在共晶固/液界面前沿的富集程度不同

导致了Sb在共晶Si表面的吸附数量不同

从而影响了共晶Si的生长速度。

Abstract

Microstructure evolution of Sr modified Al-13Si-0.4Mg alloy during solidification process was observed by quenching and OM（optical microscope） to understand the un-uniformity of eutectic structure in the alloy.The results show that

during the initial stage of eutectic reaction

coarse eutectic structure is created in the alloy as a result of low branches in formed eutectic colony

characterized by thick eutectic Si flakes with wide lamellar spacing and a few branches.With advancing in reaction

eutectic grain is gradually refined due to the increase of branches in eutectic colony

characterized by thin eutectic Si flakes with narrow lamellar spacing and a lot of branches.Different enrichment of Sb at eutectic solid-liquid solidification front results in the different absorption coefficient of Sb on surface of eutectic Si

affecting the growth velocity of eutectic Si

which is responsible for the un-uniformity of structure in the alloy.