( 1. 东南大学 材料科学与工程系, 南京 210018；
2. 盐城工学院材料科学与工程系, 盐城 224002；
3. 南京工程学院 材料科学与工程系, 南京 210023)
摘 要: 研究了Al-Sr变质剂和锆复合盐细化剂对高近共晶Al-Si合金宏观/微观组织的影响。 结果表明： 单一Al-Sr变质剂的加入， 不仅改变了共晶硅的形貌，同时对合金的组织也有较明显的细化作用。 这可能是由于锶的加入， 改变了液态金属的结构， 导致枝晶尖端前沿生长过冷度增加， 降低了枝晶/α/(Al)固液界面能。 当Al-Sr变质剂和锆复合盐细化剂共同作用时， 随着熔体中锆含量的增加，铸锭的晶粒度显著减小， 当熔体的锆含量超过0.35%， 可获得细小、 分布均匀的等轴晶， 其宏观晶粒尺寸为100~120μm。 与Al-Zr中间合金相比， 无论是细化效果还是抗衰退的能力都优于中间合金。
关键字: Al-Si合金; 变质; 晶粒细化; 宏观/微观组织
（ 1. Department of Materials Science and Engineering,Southeast University,
Nanjing 210018, China;
2. Department of Materials Science and Engineering,
Yancheng Institute of Technology,
Yancheng 224002, China;
3. Department of Materials Engineering,
Nanjing Institute of technology,
Nanjing 230013, China）
Abstract: The influence of Al-Sr modifier and Zr compound salt on marco/micro structure of near-hypoeutectic Al-Si alloys was investigated. Only the addition of Sr into Al-Si alloys could result in transition of eutectic silicon from coarse plate-like or acicular to fine fibrous, at the same time it had also a better refinement to the structure of alloys. The present of Sr in Al-Si alloys causes the changes of structures of liquid metals, and leads to the decreases of the solid-liquid interfacial energy of dendrite α(Al) and increases of the growth undercooling of dendrite tips. The combined addition of Al-Sr and Zr compound salt, with increaseing the Zr content, the grain size decreases obviously. Finer and evenly equiaxed dendrite α(Al) is attained with addition of 0.35% Zr, and the size of macrostructure grain is about 100-120μm. The Zr in compound salt forms into the Al-Si alloys melt, compared to Al-Zr master alloys, the ability of grain refinement and resistant fading are better than those of Al-Zr master alloys.
Key words: Al-Si alloys; modification; grain refinement; macro/micro structure
