This study defined hybrid additive manufacturing (AM) as “in-situ or series combination of an additive manufacturing process and secondary energy sources in which physical mechanisms are fundamentally altered/controlled to affect the resulting properties of material and/or part.” This definition includes in-situ secondary processes as well as process chains, and it is anchored in multi-physical mechanisms such that new hybrid-AM processes can be freely and systematically sought or invented through a systems approach epitomized by the “property – mechanism – energy source – hybrid-AM process (PMEH)” thought process. The sequence of driving forces in this framework are as such: desired material properties determine which mechanism is utilized and, in turn, the energy source to be applied, which ultimately defines the hybrid-AM process. The five unifying physical mechanisms that were identified in this study are: melt pool dynamics, microstructure development, stress state, surface evolution, and thermal gradients. Analysis of properties, mechanisms, energy sources, and processes was conducted on more than 100 papers, and the results ultimately show the effect of mechanisms on material properties. Mechanisms are further classified by energy source, which are in turn broken down by hybrid-AM process. Additionally, each mechanism was defined and reviewed in detail, highlighting the PMEH relationship for metal hybrid-AM materials. Further analysis compares reported mechanical property values for hybrid-AM processes to both AM only and wrought properties for 316 L, Alloy 718, and Titanium Gr 5. Finally, future directions of research as well as clear gaps in knowledge are identified, which includes lack of variety in utilized energy sources, lack of material diversity, process chain integration and improvement, and promising hybrid-AM processes. With the presented analysis and PMEH framework, it is determined that metal AM hybrid processes are well suited to address current problems and show promise in creating superior and versatile materials. Further growth in this field is expected to be exponential, and the developed PMEH framework will aid in framing these innovative processes.

这项研究将混合增材制造（AM）定义为“增材制造过程与二次能源的原位或串联组合，其物理机制从根本上被改变/控制以影响材料和/或零件的最终性能。” 该定义包括原位次级过程以及过程链，并以多种物理机制为基础，因此可以通过以“特性–机制–能源–混合AM”为代表的系统方法自由，系统地寻求或发明新的混合AM方法过程（PMEH）”的思想过程。在此框架中，驱动力的顺序是这样的：所需的材料属性决定了采用哪种机制，进而决定了要施加的能源，这最终定义了混合式AM过程。在这项研究中确定的五个统一的物理机制是：熔池动力学，微观结构发展，应力状态，表面演变和热梯度。对属性，机制，能源和过程的分析进行了100多篇论文，结果最终表明了机理对材料性能的影响。根据能量源对机制进行进一步分类，然后通过混合AM过程对其进行细分。此外，每种机理都进行了详细定义和审查，突出了金属杂化AM材料的PMEH关系。进一步的分析将报告的混合AM工艺的机械性能值与仅AM和316 L，Alloy 718和Titanium Gr 5的变形性能进行了比较。最后，确定了未来的研究方向以及知识上的明显空白，其中包括缺乏能源利用的多样性，缺乏材料多样性，过程链集成和改进以及有希望的混合AM技术。利用提出的分析和PMEH框架，可以确定，金属增材制造混合工艺非常适合解决当前的问题，并有望在制造优质多功能材料方面表现出希望。预计该领域的进一步增长将成倍增长，发达的PMEH框架将有助于构筑这些创新过程。