Dislocation damping in Cu₃Au alloys

Abstract

Dislocation damping has been measured for Cu₃Au alloys with a variety of long-range-order parameters over the temperature range room temperature to 423 K. It is found that the Cu and Au atoms on the incorrect sublattices can pin down the dislocation with an interaction energy of about -0·01 eV. A phenomenological model for the highly ordered alloy is presented in an effort to understand mechanisms of the dislocation pinning and to make a theoretical estimate of the interaction energy, which seems to be in good agreement with the experimental results. Because of the higher concentration of the pinning Cu and Au atoms, the localized degree of long-range order in the vicinity of the dislocation becomes somewhat lower than the bulk; for example, 0·96 near the dislocation compared with 0·97 in the bulk in the highly ordered Cu₃Au. It is also found that the damping is enhanced at intermediate degrees of the long-range order.