Kinetics of Surface Ordering on Au-Rich Cu3Au(001)

Abstract

Abstractwe report grazing-incidence x-ray scattering measurements of the order-disorder phase transition near a Au-rich Cu3Au (001) surface. The bulk transition temperature TB = 648 K is lower than for stoichiometric Cu3Au(001). Surface ordering persists above TB in a layer several monolayers thick up to Ts = 667 K. Kinetics of the ordering were studied by quenching from Ts + 9 K to final temperatures of TF = 661 K and 645 K. Short-range order is established in the bulk within the quench time and does not appear to change subsequently. The bulk short-range order differs from that reported for stoichiometric Cu3Au. For TB < TF = 661 K < TS, the (100) in-plane diffraction beam intensity grows approximately as t1/4 for t > 1000 s and the width continues to narrow. For TF = 645 K < TB, power law growth is not observed for the longest times studied. In both cases the growth is substantially slower than predicted.