## 3 Results and Discussion
The lower power input explained the tendency toward the smaller particle size in the case of the LPD variant well. In addition to the higher power input, a smaller beam diameter was applied in the case of the HPD manufactured material. For this reason, more surface area was re-melted and material cooling was slower, i.e., more heat and time were available for particle growth. In conventionally fabricated HiperFer 17 Cr2 (recrystallized and precipitation annealed for 2 h at 650 \({}^{\circ}\)C), the highest area-specific particle number was observed (Figure 10a). Considering the time necessary for Laves phase precipitation, the advantage of HiperFer\({}^{\text{AM}}\) clearly emerged: While the heat treatment of HiperFer 17 Cr2--including recrystallization and precipitation annealing--took more than 2 h, the heat treatment of HiperFer\({}^{\text{AM}}\) was carried out in situ despite re-melting in the range of seconds. In HiperFer 17 Cr2, as in the LPD manufactured HiperFer\({}^{\text{AM}}\), particle fractions smaller than 20 \(\upmu\)m and between 20 and 40 \(\upmu\)m were formed (Figure 10b). The width of the PFZs (approximately 300 nm) in HiperF\({}^{\text{AM}}\) was found to be independent of the area-specific laser power. Larger parameter field studies are required to evaluate to what extent the PFZ width can be tuned by the in-build heat treatment, which may have a direct effect on material ductility. Figure 8: EBSD-IFF (inverse pole figure) micrograph of the LMD-manufactured HiperF\({}^{\text{AM}}\) HPD variant in the as-built state (reproduced from [9]). Figure 9: Laves phase particles in LMD-manufactured HiperFerAM: (**a**) LPD and (**b**) HPD variants. Regions of varying particle size, such as the \"IG\({}_{\text{Exterior}}\)\" and \"IG\({}_{\text{center}}\)\" regions typically encountered in conventionally fabricated HiperFer (Figure 6), were not observed in HiperFer\({}^{\text{AM}}\). This was caused by the shorter cumulated time at high temperatures and the absence of soaking. Tensile tests were carried out to characterize the macroscopic impact of the microstructures generated in-build. The resulting UTS and total strain at rupture are depicted in Figure 11, while the corresponding values are listed in Table 3. In comparison to conventionally (rolled, recrystallized, precipitation annealed (650 \({}^{\circ}\)C/2 h)) produced 17 Cr2 sheet material, the ambient temperature tensile strength values of LMD-processed HiperFer\({}^{\text{AM}}\) were found to be higher (UTS\({}_{\text{HPD}}\): + 107 MPa, UTS\({}_{\text{LPD}}\): + 14 MPa). Figure 4:0 (**a**) UTS and (**b**) rupture elongation (A\({}_{\text{t}}\)) of the 17 Cr2 and HiperFer\({}^{\text{AM}}\) variants (LPD and HPD) at 20 \({}^{\circ}\)C and 650 \({}^{\circ}\)C. HT: * 650 \({}^{\circ}\)C/120 min, ** 650 \({}^{\circ}\)C/90 min. Figure 4:1 (**a**) Area-specific total number of particles in the as-built LPD and HPD HiperFer\({}^{\text{AM}}\) and conventional HiperFer 17 Cr2 Pa (2 h 650 \({}^{\circ}\)C) materials and (**b**) corresponding size classification by equivalent circle diameter (ECD). The advantage of HiperFer\({}^{\rm AM}\) (HPD) over HiperFer\({}^{\rm AM}\) (LPD) in terms of the UTS was caused by the smaller grain size (Figure 12) and the increased level of residual stress (i.e., higher area-specific power input). The ambient temperature rupture elongations of both the additively manufactured variants had expectedly low values of 1% (LPD) and 1.6% (HPD). In contrast, conventionally produced 17 Cr2 yielded \(\sim\)17% fracture elongation. In accordance with the encountered low fracture elongations at ambient temperature, the EBSD mappings of the additively manufactured tensile specimens present hardly any deformation (Figure 12), which was most likely caused by a comparatively high level of residual stress that resulted from the additive manufacturing process (hardness LPD/HPD 199/226 HV1, cf. Table 4).