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首页> 外文期刊>Journal of Manufacturing Processes >On an expression for the growth of secondary dendrite arm spacing during non-equilibrium solidification of multicomponent alloys: Validation against ternary aluminum-based alloys
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On an expression for the growth of secondary dendrite arm spacing during non-equilibrium solidification of multicomponent alloys: Validation against ternary aluminum-based alloys

机译：关于多组分合金非平衡凝固过程中二次枝晶臂间距增长的表达式：对三元铝基合金的验证

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摘要

The technological importance of the microstructure length scale is directly related to the influence exerted on solute redistribution and microporosity formation and on mechanical properties, such as, toughness, ductility, ultimate and yield tensile strengths. There is a huge lack of literature concerning theoretical predictive dendritic growth models for unsteady-state solidification of multicomponent alloys. Most of the existing models have been proposed for steady-state solidification and for binary alloys. One of these models, initially restricted to binary alloys, has been extended for multicomponent alloys; however, it was shown to be valid only for low growth rates and small dendrite tip undercooling, that is, conditions that are very close to those of equilibrium cooling from the melt. In this paper, an extended approach is proposed, encompassing the back diffusion parameter beta to allow back diffusion treatment to be included in the analysis. A technique based on Butler's formulation and on thermodynamic databases is used to permit necessary thermophysical parameters, such as the surface energy and the Gibbs-Thomson coefficient to be calculated for Al-Cu-(Si;Mg) alloys. Directional solidification apparatuses are used to provide a wide range of experimental solidification cooling rates and growth rates along the length of the directionally solidified castings. The model predictions are validated against the experimental scatters of secondary dendrite arm spacings of Al-Cu-Si; Mg) alloys castings solidified under transient upward and horizontal heat flow conditions. It is shown that the predictions fit quite well the experimental results.
机译：显微组织长度尺度的技术重要性直接关系到对溶质再分布和微孔形成以及机械性能（如韧性，延展性，极限抗屈强度和屈服强度）的影响。缺乏关于多组分合金非稳态凝固的理论预测树枝状生长模型的文献。已经提出了大多数现有模型用于稳态凝固和二元合金。其中一种模型最初只限于二元合金，现已扩展为多组分合金。然而，它仅对低生长速率和小的枝晶尖端过冷是有效的，也就是说，该条件非常接近从熔体平衡冷却的条件。在本文中，提出了一种扩展方法，该方法包括反向扩散参数β，以允许将反向扩散处理包括在分析中。使用基于巴特勒公式和热力学数据库的技术，可以计算出必要的热物理参数，例如可以计算Al-Cu-（Si; Mg）合金的表面能和Gibbs-Thomson系数。定向凝固设备用于沿着定向凝固铸件的长度提供广泛的实验凝固冷却速率和生长速率。针对铝-铜-硅的二次枝晶臂间距的实验散布验证了模型预测。 Mg）合金铸件在瞬态向上和水平热流条件下凝固。结果表明，预测结果与实验结果吻合良好。

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