Microstructural evolution in infiltration‐growth processed MgB2 bulk superconductors |
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| Authors: | Ashutosh G Bhagurkar Akiyasu Yamamoto Anthony R Dennis John H Durrell Talal A Aljohani Hari B Nadendla David A Cardwell |
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| Affiliation: | 1. Brunel Centre for Advanced Solidification Technology, Brunel University London, Uxbridge, UK;2. Department of Applied Physics, Tokyo University of Agriculture and Technology, Tokyo, Japan;3. Bulk Superconductivity Group, Department of Engineering, University of Cambridge, Cambridge, UK;4. National Centre for Advanced Materials, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia |
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| Abstract: | 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. |
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| Keywords: | infiltration and growth MgB2 superconductors |
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