合金凝固传热传质宏微观耦合数值研究及验证

Numerical study and validation for coupling of micro-macro heat and mass transfer during alloys solidification

建立了描述二元合金凝固的平面枝晶一维微观偏析数学模型,考虑溶质在固相中有限扩散,在液相中完全扩散。通过数值模拟,分析比较了A l-Cu和F e-C合金的微观偏析特性。同时,进一步将微观数值模型与宏观凝固实验的传热传质数学模型相耦合,实现了凝固宏微观复合尺度的全数值模拟。研究表明,数值计算结果与实验数据吻合良好,证明微观模型能较准确地反映微观质量传输并能可靠地与宏观相变传热传质模型相耦合。此外,从微观到宏观的计算结果都说明F e-C合金的凝固过程几乎接近平衡凝固。

One-dimensional plate-like dendritic model was built to describe the microsegregation during binary alloy solidification with finite solid back-diffusion and complete diffusion in the liquid. The specialties of microsegregation for Al-Cu and Fe-C alloys were analyzed and compared by simulation. Moreover, the microsegregation model was further developed to couple with the macro numerical heat and mass transfer model which simulates the macro solidification experiment and the full numerical simulation of micro-macro multiple scale coupling for solidification is realized. The numerical results are proven to be in good agreement with experimental data. It shows that the microsegregation numerical model can reflect the micro mass transfer accurately and can be coupled reliably with macro heat and mass transfer model for solidification, in addition, both the micro and macro investigation show that the solidification of Fe-C alloy progresses almost in equilibrium.