Every sintered disk was cut with a micro-slicer in order to obtain samples with millimetre dimensions and with its length along the preferential direction of the platelets. The surfaces were then polished with diamond paste from 9 µm down to 1 µm followed by a vibratory polishing step with colloidal silica suspension of 0.03 µm. Then, mirror-polished surfaces were imaged by Scanning Electron Microscopy (SEM) (SUPRA 55, Zeiss) with a low acceleration voltage of 1 kV.