Low temperature preparation of MgB₂tapes using mechanically alloyed powder

Abstract

Instead of commercially available MgB2 powder, we have used partially reacted powder prepared by mechanical alloying. This precursor powder consists of grains with a size of only a few nanometres and contains reacted MgB2, and also the starting material Mg and B, and is, therefore, more reactive than fully reacted commercial powders. Using copper as a sheath material, tapes were prepared by the usual powder-in-tube process. After annealing at relatively low temperatures (770–870 K) in inert atmosphere, the tapes have good superconducting properties. Magnetically we have measured a critical current density of 400 kA cm−2 at 4.2 K.