Additive manufacturing using preplaced powder became a widely used processing method during the last few years to build complex and precise structures. The laser beam is often used as a heat source to selectively melt the powder and create the structure layer by layer. However, during the processing, imperfections can occur. The spattering, accumulation of powder particles, and denudation effects lead to a redistribution of the powder in the powder bed, a loss of powder, and agglomerations. These effects can alter the processing of the subsequent tracks and layers. On the one hand, the track dimensions can vary by varied amounts of available powder. On the other hand, the process can become unstable due to different powder surface geometries, agglomerates, and the resulting variation of energy absorption. Therefore, this work aims to explain spattering effects during powder-bed processing, which can be used for modification of the processing parameters for spatter prevention. High-speed-imaging was used to record the powder and spatter behavior during the laser powder-bed processing from different angles. It was observed that different kinds of spattering can occur. Melt pool spattering occurs due to melt instabilities, while powder particles seem to be accelerated by vapor induced gas movement, pressure waves, and the gas flow induced by the Bernoulli-effect.

中文翻译：

---

选择性激光熔化过程中的飞溅效应

在过去几年中，使用预置粉末的增材制造成为一种广泛使用的加工方法，用于构建复杂而精确的结构。激光束通常用作热源来选择性地熔化粉末并逐层创建结构。然而，在加工过程中，可能会出现缺陷。粉末颗粒的飞溅、积聚和剥蚀效应导致粉末在粉末床中重新分布、粉末损失和结块。这些效果可以改变后续轨道和层的处理。一方面，轨道尺寸会因可用粉末的数量不同而有所不同。另一方面，由于不同的粉末表面几何形状、附聚物以及由此产生的能量吸收变化，该过程可能变得不稳定。所以，这项工作旨在解释粉末床加工过程中的飞溅效应，可用于修改工艺参数以防止飞溅。高速成像用于从不同角度记录激光粉末床加工过程中的粉末和飞溅行为。据观察，可能发生不同种类的飞溅。熔池飞溅是由于熔体不稳定而发生的，而粉末颗粒似乎被蒸汽引起的气体运动、压力波和伯努利效应引起的气流加速。据观察，可能发生不同种类的飞溅。熔池飞溅是由于熔体不稳定而发生的，而粉末颗粒似乎被蒸汽引起的气体运动、压力波和伯努利效应引起的气流加速。据观察，可能发生不同种类的飞溅。熔池飞溅是由于熔体不稳定而发生的，而粉末颗粒似乎被蒸汽引起的气体运动、压力波和伯努利效应引起的气流加速。