THE TYPE OF ORDER IN Cu-10 at. Au-EVIDENCE FROM THE DIFFUSE SCATTERING OF X-RAYS

摘要

In a recent publication, Kuhlmann et al. (Acta mater., l997, 45, 3319) claimed Cu-10 at. Au to be long-range ordered at temperatures above 473 K and as high as 723 K. This is in contrast to the gen- erally accepted phase diagram where this region is attributed to the range of solid solutions. To clarify this problem, a three-dimensional diffuse X-ray scattering experiment was performed at room temperature on a Cu-10 at. Au single crystal aged at 573 K. The Warren-Cowley short-range order parameters derived from this experiment show conclusively that only short-range order is present. Effective pair interaction parameters determined by the inverse Monte-Carlo method are somewhat different from those obtained for Cu-25 at. Au in the short-range ordered state.