TIME-RESOLVED X-RAY-SCATTERING STUDY OF ORDERING KINETICS IN BULK SINGLE-CRYSTAL CU3AU

Time-resolved x-ray scattering has been used to study ordering kinetics in single-crystal bulk Cu3Au. 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 Cu3Au is consistent with curvature-driven growth.