Fabrication and properties of 37-filaments MgB2 superconducting wires by in-situ powder-in-tube method

Abstract:

The filament fractures or wire breaks in multi core MgB₂ wire was appeared frequent while using the traditional in-situ powder in tube (PIT) method with Cu as the sheath material. For this problem, the 37 filament MgB₂ long wires with the diameter of 1 mm, sheathed with higher strength Monel alloys (Monel 400) is fabricated with compound fabrication process including rotary swage, drawing, rolling and middle annealing heat treatment。Microstracture showed that the sub component including MgB₂ filament and NbCu replacement is uniformly distributed and the Nb diffusion barrier is no breaking points. The mean diameter in MgB₂ filament is only 80 μm in final wires. The yield strength is around 759 MPa. for the as-drawn wire and 248 MPa for the sintered wire. The critical current density (J_c) and engineering current density (J_e) are arrived 2.31×10^₅ A.cm^_-2 and 3.16×10^₄A.cm^_-2 at 4.2 K、4 T respectively.