Dynamic solidification behavior during metal additive manufacturing directly influences the as-built microstructure, defects, and mechanical properties of printed parts. How the formation of these features is driven by temperature variation (e.g., thermal gradient magnitude and solidification front velocity) has been studied extensively in metal additive manufacturing, with synchrotron x-ray imaging becoming a critical tool to monitor these processes. Here, we extend these efforts to monitoring full thermomechanical deformation during solidification through the use of operando x-ray diffraction during laser melting. With operando diffraction, we analyze thermomechanical deformation modes such as torsion, bending, fragmentation, assimilation, oscillation, and interdendritic growth. Understanding such phenomena can aid the optimization of printing strategies to obtain specific microstructural features, including localized misorientations, dislocation substructure, and grain boundary character. The interpretation of operando diffraction results is supported by post-mortem electron backscatter diffraction analyses.

金属增材制造过程中的动态凝固行为直接影响打印零件的竣工微观结构、缺陷和机械性能。这些特征的形成是如何由温度变化（例如热梯度大小和凝固前沿速度）驱动的，在金属增材制造中已得到广泛研究，同步加速器 X 射线成像成为监测这些过程的关键工具。在这里，我们将这些努力扩展到通过在激光熔化过程中使用原位 X 射线衍射来监测凝固过程中的完整热机械变形。通过操作衍射，我们分析热机械变形模式，例如扭转、弯曲、破碎、同化、振荡和枝晶间生长。了解此类现象有助于优化打印策略，以获得特定的微观结构特征，包括局部取向错误、位错亚结构和晶界特征。原位衍射结果的解释得到了事后电子背散射衍射分析的支持。