MgB2/Fe superconducting tapes made using mechanically milled powders in Ar and H2 atmospheres

Fe-sheathed tapes of MgB2 with addition of SiC have been prepared by the powder-in-tube (PIT) method using a powder mixture mechanically milled in an argon or hydrogen atmosphere. The reactivity of the component powders in the mixtures, Mg, B and SiC, was significantly enhanced by mechanical milling, so that MgB2 formed faster than in tapes fabricated from a hand-milled mixture. At the same time the number of impurity phases was higher, and the impurity phases of Mg2Si and Fe2B were observed only in these tapes. Mechanical milling also induced a lower quality of MgB2, especially for tapes produced from powders milled in a hydrogen atmosphere, with a significant influence on the values of the critical temperature TC and critical field, JC.