Al-7Si-0.36Mg合金定向凝固一次枝晶臂间距实验和模拟

发布时间：2018-08-31 20:37

【摘要】：通过Al-7Si-0.36Mg合金定向凝固实验和元胞自动机模型,开展定向凝固枝晶形貌演化和一次枝晶臂间距选择过程的实验和模拟。结果表明:在给定的凝固条件下,一次枝晶臂间距范围是一个连续的变化区间。在恒定温度梯度和不同凝固速度条件下,测得Al-7Si-0.36Mg合金一次枝晶臂间距上限值(λmax)、下限值(λmin)和平均值(λave)以及生长速率之间的关系,且上限值和下限值的比值接近3。模拟结果与实验结果的吻合程度明显优于Hunt-Lu等解析模型的预测结果,表明CA模型在枝晶定向凝固过程枝晶形貌演化模拟和枝晶臂间距预测等方面的准确性。结合模拟研究和文献调研分析影响定向凝固一次枝晶臂选择的因素,包括抽拉速度v、温度梯度G、界面能大小、溶质扩散系数DL、枝晶生长取向与热流方向的偏离角度θ等。
[Abstract]:Based on the directional solidification experiment of Al-7Si-0.36Mg alloy and the cellular automata model, the experiment and simulation of the evolution of dendritic morphology and the selection of primary dendritic arm spacing were carried out. The results show that the range of primary dendritic arm spacing is a continuous range under given solidification conditions. Under the condition of constant temperature gradient and different solidification rate, the relationship between the upper bound value of primary dendritic arm spacing (位 max), lower bound value (位 min), average value (位 ave) and growth rate of Al-7Si-0.36Mg alloy is measured, and the ratio of upper bound value to lower limit value is close to 3. The agreement between the simulation results and the experimental results is better than that of the analytical model such as Hunt-Lu, which indicates the accuracy of the CA model in the simulation of dendritic morphology evolution and the prediction of dendritic arm spacing during directional dendritic solidification. The factors influencing the selection of primary dendritic arm in directional solidification were analyzed by means of simulation study and literature investigation, including pulling speed v, temperature gradient G, interface energy, solute diffusion coefficient DL, dendrite growth orientation and deviation angle 胃 of heat flux, etc.
【作者单位】：清华大学材料学院先进成形制造教育部重点实验室;
【基金】：国家重点基础研究发展计划项目(2011CB706801) 国家自然科学基金资助项目(51374137,51171089)
【分类号】：TG292

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