NEAR-NEIGHBOR MIXING AND BOND DILATION IN MECHANICALLY ALLOYED CU-FE

Extended x-ray-absorption fine-structure (EXAFS) measurements were use d to obtain element-specific, structural, and chemical information of the local environments around Cu and Fe atoms in high-energy ball-mill ed CuxFe1-x samples (x=0.50 and 0.70). Analysis of the EXAFS data show s both Fe and Cu atoms reside in face-centered-cubic sites where the f irst coordination sphere consists of a mixture of Fe and Cu atoms in a ratio which reflects the as-prepared stoichiometry. The measured bond distances indicate a dilation in the bonds between unlike neighbors w hich accounts for the lattice expansion measured by x-ray diffraction. These results indicate that metastable alloys having a positive heat of mixing can be prepared via the high-energy ball-milling process.