Phase-field modelling of gas porosity formation during the solidification of aluminium
Phase-field modelling of gas porosity formation during the solidification of aluminium
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DOI：
10.3139/146.110303
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发表时间：
2010-04
影响因子：
0.8
通讯作者：
A. Carré;B. Böttger;M. Apel
中科院分区：
文献类型：
--
作者：
A. Carré;B. Böttger;M. Apel
摘要 铝铸造产品的机械性能在很大程度上取决于其特定的材料微观结构，但可能会受到凝固阶段出现的缺陷（例如缺陷）的影响。 g。氢孔。在目前的工作中，我们重点关注与氢气泡相关的铝铸件中微孔缺陷形成的相场建模的具体问题。由于熔体和气相的比容差异较大，模型必须处理较大的体积变化。为了考虑不同的摩尔体积，提出了多组分/多相场模型的修改。它基于体积分数的考虑，包括额外的质量传输，允许在熔体中生长的氢气泡的压力相关的体积膨胀。此外，它还考虑了氢溶解度的压力依赖性。使用标准相场模型对 Al7% Si0.30% Mg 合金的微观结构形成进行的模拟与实验结果一致。改进的相场公式已应用于含氢纯铝。模拟了不同压力下液态铝中气泡的平衡状态以及凝固过程中气泡的形成。
Abstract The mechanical properties of aluminum cast products depend to a large extend on their specific material microstructure, but can be impaired by defects which appear at the solidification stage, e. g. hydrogen pores. In the present work, we focus on specific issues for the phase-field modelling of microporosity defect formation in aluminium casting connected to hydrogen bubbles. Because of the large differences in the specific volumes of the melt and gas phase, large volume changes have to be handled by the model. In order to take into account different molar volumes, a modification of a multicomponent/multiphase-field model is proposed. It is based upon volume fraction considerations including additional mass transport that allow for the pressure dependent volume expansion of hydrogen bubbles growing in the melt. Furthermore, it also considers the pressure dependency of the hydrogen solubility. A simulation of the microstructure formation for an Al7 % Si0.30 % Mg alloy using the standard phase-field model is shown to be in agreement with experiment. The modified phase-field formulation has been applied to pure aluminium containing hydrogen. The equilibrium state for a gas bubble in liquid aluminium and bubble formation during solidification have been simulated for different pressures.