2.1. Material & Surface Characterization

In the current study, the examined material was the superalloy Nickel alloy 718, also known as Inconel 718, in the form of powder (OC Oerlikon, Freienbach, Switzerland). The characterization of the feedstock powder is an essential task for metal AM procedures in order to achieve the optimal quality on the 3D printed product [8,28]. Hereupon, a Scanning Electron Microscope (SEM), was employed for the material characterization process. More specifically, the Phenom ProX Desktop SEM (ThermoFisher Scientific, Massachusetts, MA, USA) was used to examine the powder’s morphological characteristics. Furthermore, utilizing the SEM’s specialized modules, a Particle Size Distribution (PSD) analysis, as well as an Energy-Dispersive X-ray Spectroscopy (EDX), were performed on the feedstock powder, extracting that way the size of the powder particles and the exact chemical composition of the superalloy respectively. Moreover, SEM was also applied in order to examine the microstructure of the 3D-printed specimens and the fracture surface that emerged after the tensile experiments. In addition, the stereoscope Leica DMS 1000 (Leica Microsystems GmbH, Wetzlar, Germany) with a plan-apochromatic objective and magnification up to 300x coupled with the MountainsLab^® (Digital Surf, Besançon, France) software were employed to acquire high-resolution multi-focus images and to measure the surface roughness for each manufactured specimen with an accuracy of ±1 μm according to the ISO 4287 [29].