Abstract
MgB2 superconductors were prepared by annealing of a mixture of B and gas-atomized Mg powders. The superconducting onset temperature of 40 K and Zero resistance temperature of 37 K were obtained for the samples annealed at 1073 K for 50 h or annealed at 1073 K for 12 h and then 1173 K for 24 h. The annealing at higher temperatures and/or for longer times causes a reduction in superconductivity. MgB2 was also fabricated by using AZ31 or AZ91 alloy powders. The superconducting onset temperature of MgB2 made from AZ91 alloy powder decreases to 37 K due to the addition of Al.
