Microstructural evolution in infiltration-growth processed MgB₂ bulk superconductors

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Bhagurkar, AG 
Yamamoto, A 
Durrell, JH 
Aljohani, TA 

The study reports phase and microstructural evolution in MgB2 bulk superconductors fabricated by an infiltration and growth (IG) process. Three distinct stages, (1) intermediate boride formation, (2) bulk liquid Mg infiltration, and (3) MgB2 layer formation, were identified in IG process after detailed examination of series of samples prepared with varied heating conditions. The intermediate phase Mg2B25, isomorphous to β-boron, was detected prior to MgB2 phase formation in stage (1). Due to volume expansion involved in stage 1, cracks formed in the β-boron particles and propagated radially inwards during stage 3. The growing MgB2 particles sintered simultaneously with formation of grain boundaries during the process, as evidenced by the measured hardness and critical current density in these samples. From our observations, we estimate the total time needed for complete transformation to MgB2.

infiltration and growth, MgB2, superconductors
Journal Title
Journal of the American Ceramic Society
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Japan Society for the Promotion of Science (15H05519)
Authors acknowledge financial support from KACST-Cambridge Joint Centre of Excellence in Advanced Materials and Manufacturing (CAMM) based at the University of Cambridge, UK. Partial financial support from Engineering and Physical Sciences Research Council, UK (Grant: EP/K031422/1) is gratefully acknowledged.