The applicability of classical heterogeneous nucleation theory for an inoculated Al-18.6Si (wt pct) alloy was investigated. Nucleation model proposed by Perepezko was used to study heterogenous nucleation of primary silicon in phosphorus-inoculated alloys. For this system, the nucleation temperature was found to be the most crucial variable in the model. If a spherical cap model is assumed for heterogenous nucleation, then the contact angle changes only by the interfacial energy. However, the data applied to Perepezko’s model showed it changed by undercooling. Therefore, it is suggested that the Perepezko’s nucleation model is not applicable for analyzing data in inoculated hypereutectic Al-Si alloy. Instead, for the first time, the free growth model developed by Greer to study the inoculation of Aluminum by Al-Ti-B was used for the Al-18.6Si (wt pct) alloy inoculated with Al-Fe-P. The results of modeling compared with the experimental data showed that the free growth model gives a closer approximation when predicting the size of the primary silicon in the investigated alloy. Mechanical properties of the as-cast hypereutectic alloys are influenced by size and shape of the primary silicon and eutectic silicon, type, size, and frequency of entrainment defects and residual stresses. Finer silicon particles lead to higher tensile strength in the cast components. Being able to predict the size of primary silicon particles will facilitate control of the inoculation process, to enhance mechanical properties such as tensile strength. Developed model here provides a basis to predict the size of primary silicon in hypereutectic Al-Si alloys treated with phosphorous-containing inoculants.

中文翻译：

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过共晶铝硅合金中初生硅孕育数值模拟的一种新方法

研究了经典异质成核理论对接种 Al-18.6Si (wt pct) 合金的适用性。Perepezko 提出的成核模型用于研究磷孕育合金中原生硅的异质成核。对于该系统，发现成核温度是模型中最关键的变量。如果假设球冠模型用于异质成核，则接触角仅由界面能改变。然而，应用于 Perepezko 模型的数据表明它因过冷而发生变化。因此，建议 Perepezko 形核模型不适用于分析孕育过共晶 Al-Si 合金的数据。相反，Greer 为研究 Al-Ti-B 对铝的孕育而开发的自由生长模型首次用于 Al-18。接种有 Al-Fe-P 的 6Si (wt pct) 合金。与实验数据相比较的建模结果表明，在预测所研究合金中原生硅的尺寸时，自由生长模型给出了更接近的近似值。铸态过共晶合金的机械性能受初生硅和共晶硅的尺寸和形状、夹带缺陷和残余应力的类型、尺寸和频率的影响。更细的硅颗粒会导致铸造部件的拉伸强度更高。能够预测初级硅颗粒的尺寸将有助于控制接种过程，以提高机械性能，如拉伸强度。这里开发的模型为预测用含磷孕育剂处理的过共晶 Al-Si 合金中原生硅的尺寸提供了基础。