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Additive Manufacturing (AM) addresses various benefits as the build-up of complex shaped parts, the possibility of functional integration, reduced lead times or the use of difficult machinable materials compared to conventional manufacturing possibilities. Beside these advantages, the use of more than one material in a component would strongly increase the field of applications in typical AM branches as energy, aerospace or medical technology.By means of multi-material build-ups, cost-intensive alloys could be only used in high-loaded areas of the part, whereas the remaining part could be fabricated with cheaper compositions. The selection of combined materials strongly depends on the requested thermophysical but also mechanical properties. Within this contribution, examples (e. g. used in the turbine business) show how alloys can be arranged to fit together, e. g. in terms of a well-chosen coefficient of thermal expansion (CTE).As can be seen in nature, the multi-material usage can be characterized by sharp intersections from one material to the other (e. g. in case of a thin corrosion protection), but also by graded structures enabling a smoother material transition (e. g. in case of dissimilar materials which are joined together without defects). The latter is shown for an example from aerospace within this paper.Another possibility is the simultaneous placement of several materials, e.g. hard carbide particles placed in a more ductile matrix composition. These particles can be varied in size (e.g. TiC vs. WC). Also the ratio between carbides and matrix alloy can be adjusted depending on its application.Especially nozzle-based free form fabrication technologies, e.g. Laser Metal Deposition (LMD), enable the utilization of more than one material. Within this contribution, possibilities to feed more than one filler material are demonstrated. In addition, results of multi-material processes are shown. Finally, this work focuses on different (potential) applications, mainly in power generation but also for medical technology or wear resistant components.

Meanwhile laser-based Additive Manufacturing (AM) technologies such as Laser Metal Deposition (LMD) have been introduced in various fields of applications. The latter is not only used for the fabrication of complete new parts, but also for the purpose of repair and redesign. Therefore, weld beads with dimensions above 1 mm were mostly used in the past. In some cases, bead widths can even exceed 10 mm or more. However, the build-up of filigree parts by means of sub-millimeter structures has gained interest during the several last years. Fabrication of structures with small dimensions requires different process modifications along the process chain. This includes general process strategies but also adjusted system components. The changed process yields material deposition of varying geometries possibly used in aerospace, space, medical technology as well as micro tooling. Additionally, it can be also used for the repair of worn or damaged micro parts.Within this paper, the aforementioned process modifications are shown and demonstrated. In addition, high-speed process observations are discussed and, finally, fabricated parts are analyzed. The latter includes non-destructive and also destructive methods. Based on the combination of changed process elements, a stable laser-based AM procedure is presented which is already in production.

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