2.6. Microscopy

The cross-sections of the PBF-LB/M-samples were ground stepwise with SiC grinding paper from 320 to 1000 mesh and polished with diamond suspensions with a grain size from 3 to 1 μm. To determine the relative density of the samples, image analysis using a VHS 6000 digital microscope (Keyence Corporation, Osaka, Japan) was performed. Each of the investigated samples was prepared in three different layers. The density of each sample was determined from the mean value of the densities of these three layers. To investigate the particle morphology of the powders and the microstructures of the PBF-LB/M-densified samples a field-emission scanning electron microscopy of type MIRA3 (Tescan, Brno, Czech Republic) was used. The SEM operated at an acceleration voltage UA = 20 kV and a working distance WD = 9 mm. Micrographs were taken in secondary electron (SE) contrast if not stated otherwise. To determine inhomogeneities in the local chemical composition, energy dispersive X-ray spectrometry (EDS) was performed using an OXFORD X-Max 50 and the software Aztech in version AZtec 5.0 HF1 (Oxford instruments, Abingdon, UK). The working distance for EDS was set to 15 mm.