EXAFS STUDY OF BALL-MILLED ELEMENTAL NANOCRYSTALLINE POWDERS

Nanocrystalline elemental powders of Cr, Fe, Ni, and Cu were prepared by high-energy ball milling and studied using EXAFS spectroscopy. Data were acquired in total electron yield to avoid thickness effects, and a detailed analysis was performed to obtain structural parameters. Wh ile significant amplitude reduction was observed in the EXAFS signals of the bail-milled powders, reduction in first neighbor coordination n umber based on curve-fitting was limited to less than or equal to 15%. The results art consistent with the presence of nanocrystalline struc tures and structural defects induced by the milling process.