Sr变质后Al-28%Si合金中Si相的生长行为
Growth Behavior of Silicon Phase of Al-28%Si Alloy Modified with Sr
李华基， 胡慧芳， 陈俊桃
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作者单位：（重庆大学 材料科学与工程学院，重庆 400030）
中文关键字：Al-28%Si合金； Sr变质； 初生Si相； 共晶Si相
英文关键字：Al-28%Si alloy; strontium modification; primary silicon; eutectic silicon
中文摘要：采用不同的腐蚀、萃取方法，研究Sr变质后Al-28%Si合金初生Si和共晶Si相的形貌变化。结果表明，变质后合金中初生Si金相组织呈鱼骨状，萃取后是由八面体堆垛形成的长条状聚集体。SEM分析显示，Sr元素在初生硅内部并未富集，Sr的加入影响了初生硅的形核，并未影响初生Si的生长过程；变质后共晶Si表现为细而短的纤维杆状组成的脊骨状结构，能谱分析显示在共晶Si生长前端存在Sr元素的富集。游离态Sr原子在Si相表面的吸附阻止了共晶Si相的片状生长，进而形成分枝细密的珊瑚状共晶Si，Sr的加入影响了共晶Si的生长过程。
英文摘要： The microstructure evolution of primary silicon and eutectic silicon in Al-28%Si alloy modified with Sr was investigated by different corrosion and extraction methods. The results show that the microstructure of primary silicon presents fishbone shape with different lengths. Extracted from Al-28%Si alloy with chemistry reagent, the primary silicon is the strip aggregation stacked by the octahedral silicon. SEM analysis demonstrates that Sr element isn't rich in primary silicon, so Sr modification has an effect on the nucleation of primary silicon, but hasn’t on the growth processes; the eutectic silicon changes from long thin needle-shape into short rod shape. The modification of eutectic silicon mainly attributes to the enrichment of Sr at the front edge of eutectic silicon, which counteracts the eutectic Si growing up.