title: Kinetic analysis of MgB2layer formation in advanced internal magnesium infiltration (AIMI) processed MgB2wires.
abstract: Significantly enhanced critical current density (Jc) for MgB2superconducting wires can be obtained following the advanced internal Mg infiltration (AIMI) route. But unless suitable precautions are taken, the AIMI-processed MgB2wires will exhibit incomplete MgB2layer formation, i.e. reduced superconductor core size and hence suppressed current-carrying capability. Microstructural characterization of AIMI MgB2wires 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 MgB2layer is formed. A drastic drop in the Mg transport rate from infiltration to diffusion causes the termination of the MgB2core growth. To quantify this process, a two-stage kinetic model is built to describe the MgB2layer formation and growth. The derived kinetic model and the associated experimental observations indicate that fully reacted AIMI-processed MgB2wires can be achieved following the optimization of B particle size, B powder packing density, MgB2reaction activation energy and its response to the additions of dopants.
authors.affiliation: Center for Superconducting and Magnetic Materials (CSMM), Department of Materials Science and Engineering, The Ohio State University Columbus, OH 43210 USA.
authors.forename: G Z
authors.initials: GZ
authors.lastname: Li
authors.affiliation: Center for Superconducting and Magnetic Materials (CSMM), Department of Materials Science and Engineering, The Ohio State University Columbus, OH 43210 USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Sumption
authors.affiliation: Center for Superconducting and Magnetic Materials (CSMM), Department of Materials Science and Engineering, The Ohio State University Columbus, OH 43210 USA.
authors.forename: E W
authors.initials: EW
authors.lastname: Collings
keywords: AIMI; Magnesium diboride; electron microscopy; infiltration; kinetics