Al-7Si-Mg合金凝固过程形核模型建立及枝晶生长过程数值模拟

发布时间：2018-07-12 13:42

本文选题：三元铝合金 + 形核模型　；参考：《金属学报》2015年06期

【摘要】：针对铝合金砂型铸造较低冷速特点,通过实测和分析不同凝固条件下的冷却曲线,建立了适用于铝合金形核密度随最大形核过冷度呈指数性变化的形核函数.通过与Pandat软件热力学、动力学、平衡相图数据库相耦合,并利用空间坐标变化等算法,建立了适用于三元铝合金二维、三维枝晶生长的CA模型.在该模型中,同时考虑了溶质扩散、成分过冷、曲率过冷、晶体择优取向以及不同组元之间相互作用等重要因素的影响.利用建立的形核和生长模型,模拟了Al-7Si-0.36Mg合金在不同凝固条件下的二维枝晶演化及形貌特征,描述了溶质组元的分布特征以及定量地预测了二次枝晶臂间距的变化,并与实验结果进行了对比.三维枝晶的模拟结果有效反映了枝晶空间结构复杂性和多样性,并与实验结果吻合良好.
[Abstract]:According to the characteristics of low cooling rate in aluminum alloy sand mold casting, the nucleation function suitable for aluminum alloy nucleation density changing exponentially with the maximum nucleation undercooling degree was established by measuring and analyzing the cooling curves under different solidification conditions. By coupling with Pandat software thermodynamics, kinetics, equilibrium phase diagram database, and using the algorithm of space coordinate change, a CA model suitable for 2D and 3D dendritic growth of ternary aluminum alloy was established. In this model, the effects of solute diffusion, composition undercooling, curvature undercooling, crystal preferred orientation and interaction between different components are considered. Using the nucleation and growth model established, the two-dimensional dendritic evolution and morphology of Al-7Si-0.36mg alloy under different solidification conditions were simulated, the distribution characteristics of solute components and the change of secondary dendritic arm spacing were described. The simulation results of 3D dendrite reflect the complexity and diversity of dendritic space structure and agree well with the experimental results.
【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;明志科技有限公司;
【基金】：国家重点基础研究发展计划项目2011CB706801 国家自然科学基金项目51374137和51171089 国家科技重大专项项目2012ZX04012-011和2011ZX04014-052资助~~
【分类号】：TG292

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