图1.1 - AM零件的照片：（a）推进器歧管，该歧管展示了形成内部途径和空腔的能力； （b）晶格立方体，既展示了AM的重量减轻和强度能力； （c）由钛制造的钥匙扣。这些照片不仅展示了AM的实际方面，还展示了该技术的艺术可能性。............................................................................................... 1 Figure 2.1 – Graph illustrating the different material processing techniques and the time for the interaction [34]... 11图2.2 - 直接激光沉积（DED）系统的示意图。......................................................................... 11 Figure 2.3 – A detailed schematic of a direct energy deposition (DED) system......................................................... 12 Figure 2.4 – Schematics of early patents used for the development of a coaxial head: (a) Gale et al.[24]，（b）Schaefer等。[25]和（c）Livsey等。[27]。............................................................................................................. 13 Figure 2.5 – Patents of coaxial nozzle designs for comparative purposes: (a) Hammeke [28] and (b) Buongiorno [30]............................................................................................................................................................................... 14 Figure 2.6 – Simplified schematic for a coaxial head with two configurations: axial spray (left) and side spray (right) [33]............................................................................................................................................................................... 16 Figure 2.7 – Mapping of the parameters and the operating region for an DED design [51]....................................... 17 Figure 2.8 – Visual aid of a proposed beam routing system exaggerating the Gaussian profile...................................................................................................................................................................................................................................................................................................................................................................................................... reseation图证明了辐射的不同材料与波长的反射率[34]。.............................................................................................................................................................................. 20 Figure 2.10 – Early powder delivery patent schematics by Kenneth [81]................................................................... 23 Figure 3.1 – Design algorithm for DED machine design used to as a final check for the BenchDED....................... 30 Figure 3.2 – The experimental setup used in the development of the preliminary laser system.此实验设置用于确定使用两镜头配置与200瓦ND ND：YAG模块结合使用的最大点大小。The system was designed to be horizo​​ntal so that the substrate could be moved to the waist of the beam.................................................................................................................................................... 34 Figure 3.3 – Mirror beam routing system for DED............................................................................... 46 Figure 3.14 – Final design used in the research..................................................................................................... 35 Figure 3.4 – Fiber coupling systems............................................................................................................................ 36 Figure 3.5 – Schematic and photo of the first PDS prototype..................................................................................... 40 Figure 3.6 – Photos of a powder delivery system with pneumatics............................................................................. 41 Figure 3.7 – Photo of a mounted powder delivery system that used gravity to provide a consistent powder flow..... 41 Figure 3.8 – Schematic of the CAD coaxial nozzle..................................................................................................... 43 Figure 3.9 – 3D printed coaxial nozzle mock-up......................................................................................................... 43 Figure 3.10 – Testing optical assembly........................................................................................................................ 44 Figure 3.11 – Final optical assembly design................................................................................................................ 44 Figure 3.12 – Exploded view of the aluminum CNC manufactured coaxial nozzle.................................................... 45 Figure 3.13 – 2D side view of the coaxial nozzle CAD assembly........................................................................................................... 46 Figure 4.1 – Compiled and labeled photos of the BenchDED setup........................................................................... 51 Figure 4.2 – Optical microscope images at a magnification of x250 for varying the laser power density on SS316 substrates...................................................................................................................................................................... 55 Figure 4.3 – Localized vaporization of material experiments, with (a) showing a magnification of Figure 4.2 (d) and (b) showing a magnification of Figure 4.2 (e)............................................................................................................. 56 Figure 4.4 – Graph of melt pool diameter development in relation to power density................................................. 57 Figure 4.5 – The result of different scanning speeds and laser powers....................................................................... 58 Figure 4.6 – A magnified image of the outermost track from scanning rate experiments for a laser power of 125 W and scanning speeds of 50 mm/sec (left) and 200 mm/s (right).................................................................................. 59 Figure 4.7 – A comparison of the real images, versus the topology and depth mapping............................................ 60 Figure 4.8 – Optical images used to analyze the multi-pass deposition results........................................................... 61 Figure 5.1 – A photograph of the BenchDED chamber.绿色来自保护玻璃，该防护玻璃阻塞了所有红外辐射。............................................................................................. 69......................................................................................................................................................... 66 Figure 5.2 – Schematic of BenchDED G code toolpath.