期刊
ACTA MATERIALIA
卷 96, 期 -, 页码 66-71出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2015.06.013
关键词
Magnesium diboride; AIMI; Infiltration; Kinetics; Electron microscopy
资金
- NASA under SBIR [NNX14CC11C]
- NIH, National Institute of Biomedical Imaging and Bioengineering [R01EB018363]
Significantly enhanced critical current density (J(c)) for MgB2 superconducting wires can be obtained following the advanced internal Mg infiltration (AIMI) route. But unless suitable precautions are taken, the AIMI-processed MgB2 wires will exhibit incomplete MgB2 layer formation, i.e. reduced superconductor core size and hence suppressed current-carrying capability. Microstructural characterization of AIM! MgB2 wires before and after the heat treatment reveals that the reaction mechanism changes from a Mg infiltration-reaction at the beginning of the heat treatment to a Mg diffusion-reaction once a dense MgB2 layer is formed. A drastic drop in the Mg transport rate from infiltration to diffusion causes the termination of the MgB2 core growth. To quantify this process, a two-stage kinetic model is built to describe the MgB2 layer formation and growth. The derived kinetic model and the associated experimental observations indicate that fully reacted AIMI-processed MgB2 wires can be achieved following the optimization of B particle size, B powder packing density, MgB2 reaction activation energy and its response to the additions of dopants. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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