LOCAL STRUCTURAL DISTORTIONS IN QUENCHED AU-CU ALLOYS

Disordered alloys AuxCu1-x prepared by melt spinning method were analy zed by XAFS taken at 80 K. Local atomic structure around Au and Cu ato ms was measured and strong deviations from perfect fee structure were obtained resulting from the size disparity between Au and Cu atoms. A sharp asymmetry was found between the shorter (Cu-Cu) and the longer ( Au-Au) nearest neighbor bond lengths. Average first nearest neighbor d istance was found greater than obtained using linear interpolation of the pure components. Results on Debye-Waller factors showed strong con centration dependence for the Cu-Cu bond, suggesting the loosening of contact between these atoms when the concentration of Au increases.