Three-dimensional Observation of Nonmetallic Inclusion Clusters in Solid Metal by X-ray Micro-CT

In this study, we developed a method of observing three-dimensional (3D) inclusion clusters in metal. The theory of X-ray micro-computed tomography (CT) is generally introduced. The criteria on determining the sample size and energy of X-ray beam is set according to the characteristics of the beamline BL20XU available at Spring-8, which is the largest synchrotron radiation facility. The Al-TiB2 and Al-SiC system were measured by the X-ray micro-CT available in beamline BL20XU at Spring-8. The determination of the sample size the energy of X-ray beam are discussed on basis of the X-ray linear attenuation coefficient (LAC) and the transmission rate of Al-TiB2 and Al-SIC system. The limitation of the charge coupled device (CCD) camera, such as spatial resolution and observing field, are taken into consideration as well. Phase retrieval method is applied to reduce the noises of tomographic images for Al-SiC system due to its poor contrast. The 3D particle clusters of TiB2 and SiC are reconstructed by self-developed program. The fractal dimension of TiB2 and SiC clusters are calculated around 2.7. The feasibility of observing alumina cluster in steel is discussed on basis of the latest capability of beamline BL20XU at Spring-8.