MgB2 tapes made of mechanically alloyed precursor powder in different metallic sheaths

MgB2 tapes have been made by the powder-in-tube technique using precursor powder prepared by mechanical alloying and deformed in Fe, Nb and Ti sheaths by two-axial and flat rolling. The best core uniformity and the highest core density were obtained for Ti sheathed tape. Different Jc values and current anisotropies were measured for applied sheath materials after the same deformation and heat treatment at 600 deg. C for 3 h or at 650 deg. C for 0.5 h, which is discussed and related to the interface reaction and to MgB2 core density and texture. The MgB2/Ti tape having the strongest sheath and the smoothest core/sheath interface has the best texture of MgB2 and consequently also the largest anisotropy ratio