Superconducting Properties of MgB₂ Particle Impregnated with Mg-Based Alloys

Abstract

The three-dimensional penetration method combined with semi-solid casting (SS-3DPC) was utilized to prepare magnesium diboride (MgB₂) powder composite materials with various host materials of Mg, Mg-3%Al, Mg-3%Al-1%Zn, Mg-9%Al, and Mg-9%Al-1%Zn. X-ray diffraction measurements indicated predominant peak patterns of MgB₂ and a host alloy, implying that the host material tightly bonded MgB₂ grains without melting the MgB₂ powder. This was confirmed by SEM images. Measured electrical resistivity and magnetization versus temperature showed clear signals of superconducting transition temperature of 27∼38 K for all the samples cut out from the billets. Magnetic hysteresis loop observed at 5 K enabled us to estimate a critical current density (J_c) based on the extended Bean model. Additions of aluminum and zinc elements to magnesium host-matrix were found to enhance J_c and increase residual resistivity (ρ₀) suggesting that aluminum and zinc have an effect on pinning magnetic flux flow for J_c enhancement, and scattering conduction electrons for increase of ρ₀.