Improved Hc2 in Bulk-Form Magnesium Diboride by Mechanical Alloying With   Carbon
  High energy milling of MgB2 pre-reacted powder renders the material largely amorphous through extreme mechanical deformation and is suitable for mechanically alloying MgB2 with dopants including carbon. Bulk samples of milled C and MgB2 powders subjected to hot isostatic pressing and Mg vapor annealing have achieved critical fields in excess of 32T and critical current density approaching 10^6 A/cm^2. 
B. J. Senkowicz, J. E. Giencke, S. Patnaik, C. B. Eom, E. E. Hellstrom   and D. C. Larbalestier