Directed energy deposition (DED) is a branch of additive manufacturing (AM) processes in which a feedstock material in the form of powder or wire is delivered to a substrate on which an energy source such as laser beam, electron beam, or plasma/electric arc is simultaneously focused, thus forming a small melt pool and continuously depositing material, layer by layer. DED has several unique advantages compared to other AM processes, such as site-specific deposition and repair, alloy design, and three-dimensional printing of complex shapes. Herein, recent advances as well as the main aspects governing laser-material interactions during the DED process, melt pool thermal behavior, advanced in situ monitoring, and interaction mechanisms are critically reviewed. The most critical processing variables and their influence on the deposited material properties, along with defect formation mechanisms and characterization techniques, are also identified and discussed. An overview of high-end applications, current challenges associated with DED processing, and a critical outlook of the technology are presented.

定向能量沉积 (DED) 是增材制造 (AM) 工艺的一个分支，在该工艺中，将粉末或线材形式的原料材料输送到基板上，在基板上使用激光束、电子束或等离子/电等能量源。电弧同时聚焦，从而形成一个小的熔池并逐层连续沉积材料。与其他 AM 工艺相比，DED 具有几个独特的优势，例如特定位置的沉积和修复、合金设计以及复杂形状的 3D 打印。在此，最新进展以及在 DED 过程中控制激光与材料相互作用的主要方面、熔池热行为、原位先进监督和互动机制受到严格审查。还确定和讨论了最关键的工艺变量及其对沉积材料特性的影响，以及缺陷形成机制和表征技术。介绍了高端应用的概述、与 DED 处理相关的当前挑战以及该技术的重要前景。