Critical Behavior and Scaling Law in Ordering Process of the First Order Phase Transition in Cu3Au Alloy

Time resolved X-ray scattering experiments have been carried out to investigate the kinetics of configurational ordering process in Cu 3 Au alloy in the vicinity of its order-disorder phase transition point. In the later stage of the ordering process, we observe that the X-ray diffraction profiles show universal scaling property in terms of space and time; when reciprocal space and time are scaled properly, the observed diffraction spectra give a common functional form irrespective of the quench depth. The experimental scaling function is expressed simply by a squared Lorentzian curve. It is also seen that the critical droplet size and the incubation time which give the scaling parameters with respect to space and time critically diverge as the quench depth is reduced to zero.