Metal additive manufacturing has seen extensive research and rapidly growing applications for its high precision, efficiency, flexibility, etc. However, the appealing advantages are still far from being fully exploited, and the bottleneck problems essentially originate from the incomplete understanding of the complex physical mechanisms spanning from the manufacturing processes, microstructure evolutions, to mechanical properties. Specifically, for powder-fusion-based additive manufacturing such as laser powder bed fusion, the manufacturing process involves powder dynamics, heat transfer, phase transitions (melting, solidification, evaporation, and condensation), fluid flow (gas, vapor, and molten metal liquid), and their interactions. These interactions induce not only various defects but also complex thermal-mechanical-compositional conditions. These transient conditions lead to highly non-equilibrium microstructure evolutions, and the resultant microstructures, together with those defects, can significantly alter the mechanical properties of the as-built parts, including strength, ductility and residual stress. We believe that the most efficient approach to advance the fundamental understanding is integrating in-situ experimentation and high-fidelity modeling. In this review, we summarize the state of the art of these two powerful tools: in-situ synchrotron experimentation and high-fidelity modeling, and provide an outlook for potential research directions.

金属增材制造以其高精度、高效性、灵活性等优点得到了广泛的研究和迅速增长的应用，但其诱人的优势还远没有得到充分发挥，瓶颈问题本质上源于对复杂物理机制的不完全理解。从制造工艺、微观结构演变到机械性能。具体来说，对于基于粉末熔融的增材制造（例如激光粉末床熔融），制造过程涉及粉末动力学、传热、相变（熔化、凝固、蒸发和冷凝）、流体流动（气体、蒸气和熔融金属）液体）及其相互作用。这些相互作用不仅会引起各种缺陷，还会引起复杂的热机械成分条件。这些瞬态条件导致高度不平衡的微观结构演变，由此产生的微观结构以及这些缺陷可以显着改变竣工零件的机械性能，包括强度、延展性和残余应力。我们相信，推进基本理解的最有效方法是整合现场实验和高保真建模。在这篇综述中，我们总结了原位同步加速器实验和高保真建模这两种强大工具的最新技术，并为潜在的研究方向提供了展望。