金属激光增材制造过程中熔池处于超高温度梯度、超快凝固速率、循环热载荷的极端非平衡凝固环境中，复杂的材料冶金、热力耦合行为容易导致孔隙、裂纹等缺陷的产生，影响构件的内部质量与力学性能。 受限于材料的不透明性，传统的材料表征方法难以实现金属激光增材制造过程中的实时信息捕捉。 相比之下，同步辐射 X 射线成像具有高时空分辨率，可以实现金属激光增材制造过程中熔池动力学及缺陷衍化的原位表征。 论文综述了同步辐射 X 射线成像在金属激光粉末床熔融增材制造领域的研究进展，总结了增材构件中常见的缺陷类型及其表征手段，详细介绍了增材制造过程中熔池动力学行为及缺陷衍化机制，最后对同步辐射 X 射线成像在增材制造领域的未来发展方向进行了展望。

In the process of metal laser additive manufacturing, the extreme nonequilibrium solidification environment withultrahigh temperature gradients, ultrafast solidification rates and cyclic thermal loads of the melting pool can easily lead tothe generation of defects such as pores and cracks, which affect the internal quality and mechanical properties of thecomponents. Traditional material characterization methods are limited by the opacity of materials, making it difficult tocapture real-time information during metal laser additive manufacturing. In contrast, synchrotron X-ray imaging has highspatiotemporal resolution and can be used to realize in situ characterization of melting pool dynamics and defect evolutionduring metal laser additive manufacturing. This article reviews the research progress of synchrotron X-ray imaging in thefield of metal laser powder bed fusion additive manufacturing, summarizes common types of defects in additivecomponents and their characterization methods, and provides a detailed introduction to the melting pool dynamics anddefect evolution mechanisms during additive manufacturing. Finally, the future research trend of synchrotron X-ray imagingin the field of additive manufacturing is discussed.