The dynamics of laser spot melting and metallic alloy solidification are investigated through synchrotron x-ray radiography, 3D electron backscatter diffraction data, and computational fluid dynamics (CFD) simulations on a model NiMoAl alloy. Solidification velocities are measured from images to validate a CFD model of the spot melt. TriBeam tomography is used to reconstruct the melt pool in 3D, characterize the microstructure, and validate the CFD model melt pool dimensions. 3D geometrically necessary dislocation (GND) density calculations reveal extensive deformation at the sample surface. GND calculations integrated with the CFD model reveal that the halo of small, equiaxed grains adjacent to the fusion line is a result of recrystallization that occurred in the heat affected zone. By combining and data modalities across a variety of temporal and spatial length scales, the microstructure formation mechanisms and their relationship to melt pool solidification are quantified.

中文翻译：

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模拟增材制造过程中熔池动力学和微观结构的量化

通过同步加速器 X 射线射线照相、3D 电子背散射衍射数据和 NiMoAl 合金模型的计算流体动力学 (CFD) 模拟，研究了激光点熔化和金属合金凝固的动力学。通过图像测量凝固速度，以验证点熔的 CFD 模型。TriBeam 断层扫描用于以 3D 方式重建熔池、表征微观结构并验证 CFD 模型熔池尺寸。3D 几何必要位错 (GND) 密度计算揭示了样品表面的广泛变形。与 CFD 模型相结合的 GND 计算表明，邻近熔合线的小等轴晶粒的晕圈是热影响区发生再结晶的结果。通过组合各种时间和空间长度尺度的数据模态，可以量化微观结构形成机制及其与熔池凝固的关系。