Property-microstructure analysis and statistical qualification of MgB2 bulks: An investigation via micrograph feature extraction

Abstract

In the pursuit of high-quality superconductors for stable operation at cryogenic temperatures, the understanding of process-structure-property relationships is crucial to device performance reproducibility and scalability. In this manuscript, we propose an indirect image-based method to evaluate statistical relationships between the ex-situ characterization results (i.e., superconducting, and mechanical properties) and microstructural distribution of MgB2 bulks produced via Spark Plasma Sintering. This study utilizes bulks processed under similar temperature profiles and sintering time, but different uniaxial loads and powder modalities. Considering the microstructure as the centerpiece between the MgB2 sintering thermodynamics and yielded macroscopic properties, multiple cross-sectional SEM micrographs of bulks MgB2 undergo an automated process that comprise image thresholding, segmentation, masking, and filtering to enable the identification of microstructural defects and byproducts. The statistical analysis establishes the relationship between processing conditions, bulk microstructural distributions, and ex-situ characterization results. Lastly, morphological analysis of the bulk cross-section microstructures indicates the effectiveness of the proposed method in identifying and statistically quantifying property variation in MgB2 bulk properties.