In laser-based directed energy deposition (DED) additive manufacturing, interactions among the laser beam, particle flow, and melt pool influence the properties of the solidified final part. Two separate DED systems, one with high powder flow rates to represent industrial-scale DED processing and the other with low powder flow rates for individual particle tracking, were synchronized with the high-speed imaging setup at the Advanced Photon Source in Argonne National Laboratory. In-situ x-ray imaging of the DED process using both systems highlighted the influence of powder flow rates. Increased powder flow rates resulted in less laser absorption into the melt pool, leading to a transition from a keyhole mode to a melt pool without a keyhole but with surface fluctuations due to powder flow. Increased velocities of particles during powder flow resulted in a decrease in particle melting times and a greater propensity for porosity formation. Overall, better understanding of the interactions that occur during various scales of the DED process will enable flexibility, control, and new materials development in DED-based additive manufacturing.

中文翻译：

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使用高速 X 射线成像对定向能量沉积增材制造进行原位观察

在基于激光的定向能量沉积 (DED) 增材制造中，激光束、粒子流和熔池之间的相互作用会影响固化最终部件的性能。两个独立的 DED 系统，一个具有代表工业规模 DED 处理的高粉末流速，另一个具有用于单个粒子跟踪的低粉末流速，与阿贡国家实验室高级光子源的高速成像设置同步。使用这两种系统对 DED 过程进行的原位 X 射线成像突出了粉末流速的影响。增加的粉末流速导致熔池中的激光吸收减少，导致从小孔模式过渡到没有小孔但由于粉末流动而导致表面波动的熔池。粉末流动期间颗粒速度的增加导致颗粒熔化时间的减少和孔隙形成的更大倾向。总体而言，更好地了解在 DED 过程的各种规模期间发生的相互作用，将使基于 DED 的增材制造的灵活性、控制和新材料开发成为可能。