An interface diffusion process approach for the fabrication of MgB2wire

We propose a new approach for the fabrication of MgB2 tape utilizing an interface diffusion reaction between an Fe?Mg alloy substrate and a boron (B) layer. The Fe?Mg alloy has enough workability to be deformable into a tape form, and the Fe?Mg/(B(+ SiC)) composites were prepared by a lamination method. During the heat treatment at 700??C, the Mg in the Fe?Mg alloy diffuses towards the interface, forming a thin Mg rich layer along the interface. The Mg rich thin layer acts as a source of Mg for MgB2 formation, which proceeds to the inside of the B layer. Such a formation mechanism produces a dense structure of MgB2 with much less MgO impurity, which is difficult to achieve by the conventional powder-in-tube (PIT) process. SiC addition to the B layer is effective for improving the critical current density Jc in applied magnetic fields as in the case of the PIT process, and a Jc value of 3 ? 104?A?cm?2 at 5?K and 7?T has been obtained, which is comparable to that of PIT tape with SiC addition. This approach is expected to be a breakthrough in the development of MgB2 wire with a high quality superconducting layer in the composite.