【摘要】 激光粉末床熔融中匙孔、熔池和颗粒飞溅等具有高度动态、瞬变、空间尺度小等特点，对粉末熔化过程进行原位高速成像有助于深入揭示熔道及缺陷形成机制。实验基于高分辨率的开放式微焦点X射线管，开发了激光粉末床熔融原位成像系统，开展了316L粉末熔融过程匙孔、气泡、飞溅及球化等现象观测研究。结果表明，该系统可识别出保护气与熔池界面的动态变化，观测到部分激光工艺参数下匙孔的形貌变化，捕捉到匙孔诱导大尺度气孔（约100μm）的形成过程；同时发现，较高的射线管电压（如220 kV）有助于提升系统对熔池的辨别能力，但由于此时X射线对飞溅的穿透性过强，造成小尺寸飞溅无法成像；较低的射线管电压下（如90kV），系统可较好地捕捉飞溅（约30μm以上）的运动行为，初步揭示了飞溅诱导熔道表面突起、高度尺寸偏差及表面波纹等缺陷的形成机制，再现了球化现象的动态形成过程。该技术的开发对加快增材制造材料及工艺的原位研究具有重要意义。更多还原

【Abstract】 Laser powder bed fusion(LPBF) processes exhibit highly dynamic, transient, and spatially small-scale characteristics such as keyholes, melt pools, and particle spattering. Conducting in-situ high-speed imaging of powder melting processes aids in deepening our understanding of melt pool dynamics and defect formation mechanisms. This study developed an in-situ imaging system for LPBF using a high-resolution open micro-focus X-ray tube. Observational research focused on phenomena including keyholes, bubble, spattering, and balling during the melting of 316L powder. The results demonstrate the system’s capability to detect dynamic changes at the gas/melt pool interface and capture morphological changes of keyholes under certain laser process parameters, including the formation process of keyhole-induced large-scale porosity(～100 μm). Furthermore, it is found that higher X-ray tube voltages(e.g., 220 kV) enhance the system’s ability to discern melt pools, although excessive X-ray penetration at this level prevents imaging of small-sized spatters. Conversely, lower X-ray tube voltages(e.g., 90 kV) effectively capture spattering behavior(～30 μm and above), preliminarily revealing mechanisms such as spatterinduced surface protrusions, significant dimensional deviations, and surface rippling defects in melt tracks. Additionally, dynamic processes of balling are replicated. The development of this technology holds significant implications for advancing in-situ studies of materials and processes in additive manufacturing.更多还原