Development of carbon-doped ex situ MgB2 wire by mechanical alloying

Carbon-doped ex situ MgB2 wires were fabricated using a mechanical alloying (MA) method and the effect of the milling time on the phase formation, lattice change, and critical properties was investigated. The precursor powder was prepared with a mixture of MgB2 and 1 at% carbon black (CB) powder by mechanical alloying for 0-100 h. The MA process effectively decreased the powder size and increased the structural disorder of the powders, while it did not provide the incorporation of C in the MgB2 powders. On the other hand, C doping occurred successfully in the MA-treated wires after sintering. The addition of CB and the MA process improved the J(c)(B) and flux pinning force. These improvements are related to the combined effects of the smaller grains, more severe structural disorder, and higher level of CB doping by the MA process. (C) 2009 Elsevier B.V. All rights reserved.