Application of Serial Sectioning to Evaluate the Performance of x-ray Computed Tomography for Quantitative Porosity Measurements in Additively Manufactured Metals

This study presents a correlative characterization of internal porosity within a Ti-6Al-4V (Ti64) additively manufactured sample. An x-ray computed tomography (XCT) reconstruction is compared to a mechanical polishing-based serial sectioning (SS) reconstruction over the same volumetric region. A 10-mm-diameter cylindrical additive manufactured sample was examined in this study, which was manufactured by laser powder bed fusion out of Ti64 virgin powder. Microfocus XCT imaging was conducted to characterize the internal porosity within the sample, at a voxel resolution of approximately 23 µm. After XCT imaging, a custom SS system was employed for optical microscopy characterization at a much finer spatial resolution—approximately 22 times—compared to the XCT reconstruction. The SS data were correlated with the XCT images of the sample. The methods used for segmentation of each data volume are discussed. The quantitative results of stereology, area fraction of porosity, and equivalent pore diameters are presented. The comparative results for manual data registration are also presented, as well as the future direction of research resulting from this current study.