Microstructural evolution in infiltration‐growth processed MgB2 bulk superconductors. Issue 6 (25th March 2017)

• Record Type: Journal Article
• Authors: Bhagurkar, Ashutosh G.; Yamamoto, Akiyasu; Dennis, Anthony R.; Durrell, John H.; Aljohani, Talal A.; Nadendla, Hari B.; Cardwell, David A.
• Is Part Of: Journal of the American Ceramic Society. Volume 100:Issue 6(2017)
• Page Start: 2451
• Page End: 2460
• Publication Date: 2017-03-25
• Subjects: infiltration and growth -- MgB2 -- superconductors; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.14792
• Languages: English
• ISSNs: 0002-7820

Abstract

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 Mg2 B25, 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 .