X-Ray Computed Tomography Study of the Microstructure of Superconducting MgB2 Bulks

Abstract MgB 2 is a promising candidate for commercial superconducting applications because, as grain boundaries in MgB 2 are not weak links, there are fewer limitations on the choice of processing technique compared to high-temperature superconducting (HTS) cuprates. MgB 2 bulks are usually manufactured by powder processing techniques followed by a sintering process. After sintering, the impurity phases such as MgO and MgB 4 along with porosity are formed which strongly affect the superconducting properties mainly the macroscopic path for supercurrent in MgB 2 bulks. Investigation of these microstructural features is essential to improve the superconducting properties of these bulks. In this work, high-resolution laboratory X-ray computed tomography (XCT) has been used to investigate the microstructure of MgB 2 bulks in three dimensions. The volume fraction of defects and impurity phases along with the size distribution of pores have been studied using this advanced technique. A comparison has been made between the data extracted from conventional characterization techniques such as XRD and SEM and those obtained from the advanced XCT analysis.