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Microstructural evolution in infiltration‐growth processed MgB 2 bulk superconductors
Author(s) -
Bhagurkar Ashutosh G.,
Yamamoto Akiyasu,
Dennis Anthony R.,
Durrell John H.,
Aljohani Talal A.,
Nadendla Hari B.,
Cardwell David A.
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14792
Subject(s) - materials science , infiltration (hvac) , superconductivity , boron , boride , phase (matter) , grain boundary , grain growth , analytical chemistry (journal) , mineralogy , condensed matter physics , composite material , microstructure , chemistry , chromatography , physics , organic chemistry
The study reports phase and microstructural evolution in MgB 2 bulk superconductors fabricated by an infiltration and growth ( IG ) process. Three distinct stages, (1) intermediate boride formation, (2) bulk liquid Mg infiltration, and (3) MgB 2 layer formation, were identified in IG process after detailed examination of series of samples prepared with varied heating conditions. The intermediate phase Mg 2 B 25 , isomorphous to β‐boron, was detected prior to MgB 2 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 MgB 2 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 MgB 2 .