Electron beam additive manufacturing is an effective method for the fabrication of complex metallic components. With rapid solidification, the characteristics of microsegregation within the interdendritic region are interesting and important for the subsequent phase transformation and final mechanical properties. However, in view of the microsecond lifetime and the small length scale of the molten pool, experimentally investigating microsegregation is challenging, even with electron probe micro-analysis. In this study, a multiphase-field model coupled with the real thermodynamic data of Ti6Al4V alloy was successfully developed and applied to simulate the rapid solidification of columnar β grains via electron beam additive manufacturing. The thermal gradient (G) and cooling rate (R) were obtained from a 3D powder-scale multiphysics simulation and provided as inputs to a multiphase-field model. The effects of the electron beam process parameters and thermal conditions on the columnar β grains were investigated. Liquid films and droplets were observed to have solute enrichment in the intercellular region. The size of the liquid film increased at a lower scanning speed and energy power. Increasing the scanning speed and energy power refined the columnar β grains and decreased the liquid film size. The extent of microsegregation considerably increased at lower energy power, whereas the change in scanning speed had little effect on the microsegregation. The results also indicate that solute vanadium results in significant solute trapping and microsegregation during the rapid solidification of the Ti6Al4V alloy.

电子束增材制造是制造复杂金属部件的有效方法。随着快速凝固，枝晶间区域内的微偏析特征对随后的相变和最终机械性能很重要并且很重要。然而，鉴于微秒寿命和熔池的小长度尺度，即使使用电子探针微分析，对微偏析的实验研究也具有挑战性。在本研究中，成功​​开发了结合 Ti6Al4V 合金真实热力学数据的多相场模型，并应用于通过电子束增材制造模拟柱状β晶粒的快速凝固。热梯度 ( G ) 和冷却速率 (R ) 是从 3D 粉末尺度多物理场仿真中获得的，并作为多相场模型的输入提供。研究了电子束工艺参数和热条件对柱状β晶粒的影响。观察到液膜和液滴在细胞间区域具有溶质富集。液膜的尺寸在较低的扫描速度和能量功率下增加。提高扫描速度和能量功率细化柱状β颗粒并减小液膜尺寸。微偏析的程度在较低能量功率下显着增加，而扫描速度的变化对微偏析几乎没有影响。结果还表明，在 Ti6Al4V 合金的快速凝固过程中，溶质钒导致显着的溶质俘获和微观偏析。