Time-resolved x-ray scattering has been used to study ordering kinetics in single-crystal bulk ${\mathrm{Cu}}_3$Au. After annealing at high temperatures, the sample is rapidly quenched to fixed temperatures below the order-disorder transition temperature. The development of order is monitored in real time with use of scattering techniques. The data clearly showed three regimes: nucleation, ordering, and coarsening. The anisotropic superlattice peaks that reflect the domains structure are investigated in connection with the ordering kinetics. The line shape of the scattering function exhibits a crossover from a Gaussian to a Lorentzian squared as the system goes from the ordering regime to the coarsening regime. The line shape of S(Q) is analyzed by fitting the data with a variety of functions. The resolution is accounted for during the fitting. The coarsening in ${\mathrm{Cu}}_3$Au is consistent with curvature-driven growth.

• Received 2 January 1992

DOI:https://doi.org/10.1103/PhysRevB.46.40