Superconducting Ag- or Cu-sheathed MgB2 wires were fabricated by using conventional powder-in-tube techniques. The in situ reactions of Mg and B powders with atomic proportions of 1:2 and 1.33:2 within Ag or Cu tubes at low temperatures were studied. Active alloying of Mg with Ag or Cu sheaths at temperatures below 660C was observed. For Ag sheaths, there was strong diffusion of Mg, which did not permit the formation of large amounts of MgB2 at the core. For Cu sheaths, the diffusion of Mg was stopped by the formation of a MgCu2 layer around the superconducting core. A certain excess of Mg led to superconducting cores with TC  39K and good JC values. Thus, the development of Cu/MgB2 composite wires had been proved to be possible.

Study of Ag and Cu/MgB2 Powder-in-Tube Composite Wires Fabricated by in situ Reaction at Low Temperatures. E.Martínez, L.A.Angurel, R.Navarro: Superconductor Science and Technology, 2002, 15, 1043-7