Discussion of “Effect of Strontium and Phosphorus on Eutectic Al-Si Nucleation and Formation of β-Al5FeSi in Hypoeutectic Al-Si Foundry Alloys”*
Discussion of “Effect of Strontium and Phosphorus on Eutectic Al-Si Nucleation and Formation of β-Al5FeSi in Hypoeutectic Al-Si Foundry Alloys”*
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DOI：
10.1007/s11661-009-9804-6
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
J. Campbell
中科院分区：
文献类型：
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作者：
J. Campbell
在Al-Si亚共晶合金的凝固过程中，Si的形核似乎是由于一系列形核基质在逐渐降低的温度下运行的结果：(1)AlP，其通常的颗粒形态可以启动致密的Si颗粒的形成，正如在过共晶合金中所看到的那样；(2)氧化物双线，其平面形状产生片状的Si形态；以及(3)一种目前未知的形核材料，它启动了珊瑚共晶生长形态。当在颗粒上启动时，相应的生长形式是颗粒状的；当在氧化膜上启动时，粗板(未经修饰)的生长形式为颗粒状。然而，当氧化膜被锶钝化时，共晶被迫在较低的形成温度下生长，从而形成细小的珊瑚形态，称为“变质”硅。随着锶加入量的增加，每个衬底依次被逐渐消除，从而实现了从“未改性”到改性结构的转变。
The nucleation of Si during the solidification of Al-Si hypoeutectic alloys appears to result from a hierarchy of nucleating substrates operating at progressively lower temperatures: (1) AlP, whose generally particulate morphology can initiate the formation of compact Si particles as seen in hypereutectic alloys; (2) oxide bifilms alone, whose planar form creates platelike Si morphologies; and (3) a currently unknown nucleant that initiates the coral eutectic growth morphology. The consequential growth forms are particulate when initiated on particles and coarse (unmodified) plates when initiated on oxide films. However, when oxide films are deactivated by Sr, eutectic is forced to grow at a lower formation temperature with a consequently fine coral morphology known as “modified” Si. Increasing Sr additions progressively eliminate each substrate in turn to effect the change from the “unmodified” to the modified structure.