Abstract.

Electron beam additive manufacturing (EBAM) is an emerging additive manufacturing technology with extremely high energy beam. The rapid solidification in the molten pool is of interest but not fully understood. In EBAM, with both large thermal gradient and cooling rate, the microstructure evolution during solidification is difficult to be described. The quantitative multi-phase-field model provides an effective way to reveal the dynamic evolution of dendrites in the molten pool of EBAM. In this study, the thermal profile is interpolated from the macroscale simulation at each time-step, to couple the realistic thermal evolution in the molten pool. The microstructure evolution and competitive growth have been investigated in details. Simulations of dendrite arrays with the same orientation showed how the growth velocity and the primary spacing of columnar dendrites depend on thermal gradient and cooling rate. The results are in agreement with theoretical models qualitatively. Moreover, the Gaussian nucleation model was introduced so as to give a better prediction of the microstructure in EBAM.

Graphical abstract

中文翻译：

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电子束增材制造中微观结构演变的相场模拟。

摘要。

电子束增材制造（EBAM）是一种新兴的增材制造技术，具有极高的能量束。熔池中的快速固化值得关注，但尚未完全了解。在EBAM中，具有大的热梯度和冷却速率，难以描述凝固过程中的微观结构演变。定量多相场模型为揭示EBAM熔池中枝晶的动态演化提供了一种有效的方法。在这项研究中，在每个时间步长的宏观模拟中都插入了热剖面，以耦合熔池中的实际热演化。详细研究了微观结构的演变和竞争性增长。具有相同取向的枝晶阵列的模拟表明，柱状枝晶的生长速度和初始间距如何取决于热梯度和冷却速率。结果定性与理论模型吻合。此外，引入了高斯成核模型，以便更好地预测EBAM中的微观结构。

图形概要