In-Situ Processing of Superconducting MgB2-Metal Composites

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The proposal is on the processing of magnesium boride (MgB2) using reaction synthesis involving pressure infiltration of B fibers with molten magnesium to form a continuous MgB2 phase in an Mg matrix. A major goal is to achieve superconducting applications at temperatures in excess of 25K. The influence of processing temperature, volume fraction of boron, size and shape on the resulting microstructures will be studied using various characterization techniques including metallography, microprobe, secondary ion mass spectroscopy, synchrotron x-ray tomography and transmission electron microscopy. The mechanical and superconducting properties of reacted MgB2 fibers and MgB2-metal composites will be assessed and correlated with the microstructures. Experimental studies will be followed by modeling efforts first using 1-dimensional model to predict fracture strength and elastic modulus of boron fibers followed by classical and three-phase self-consistent methods for composites. The ultimate goal of the project is to generate a science-base understanding of the synthesis of MgB2 from solid B and liquid Mg for the fabrication of continuous lengths of superconducting metal-MgB2 composite wires. The research emphasizes the development of a process for creating continuous, low-cost metal-MgB2 composite superconducting wires with a critical temperature of 39 K, through a science-based, predictive understanding of the materials science issues involved with synthesis, structure and properties of these composites.Operation of the composite superconducting wires at 25-30 K without helium cryo-cooling will result in a significant drop in costs as compared to current Nb3Sn-type wires cooled by liquid helium, which is an expensive, non- renewable resource. Possible applications include superconducting magnets for energy storage devices, levitation systems (for trains), motors, wires for power transmission and superconducting quantum interference device (SQUID) systems. The research provides opportunities for undergraduate and graduate students as well as high school teachers through outreach programs for laboratory experience involving materials processing and characterization techniques. Plans include creation of a website on MgB2 synthesis and collaboration with Argonne National Laboratory through the use of Advanced Photon Source.