Superconducting properties and workability of SS/Fe sheathed MgB₂ thin wires

Abstract

MgB₂ superconducting thin wires have been prepared by in-situ powder-in-tube process. Using Magnesium hydride MgH₂ and amorphous B powders with SiC nano-sized powder addition, SS/Fe/MgB₂/ steel composite wires of 0.53 mm ∼ 0.19 mm in diameter have been fabricated through grooved rolling and drawing. The stainless steel sheath was hardened to a Vickers hardness of around 600 Hv by cold drawing. The Ic at 4.2 K and self-field for the MgB₂ wire of 0.53 mm in diameter without SiC addition is 200 A, which corresponds to the critical current density (Jc) of 4,300 A/mm². The MgB₂ composite thin wires sheathed with low thermal conductive metals are promising as current leads with small heat leakage in liquid hydrogen.