X-ray scattering study of early stage spinodal decomposition in Al_0.62Zn_0.38

In situ small-angle x-ray scattering studies of the spinodal decomposition kinetics in an AlZn alloy at the critical composition have been performed with a time resolution of 10 ms. The kinetics of fluctuation relaxation above the critical point merges smoothly with the early-stage kinetics of fluctuation growth below Tc. Strong nonlinearities are present at the earliest times measured, even above the critical point. The nonlinear theory of Langer, Bar-on, and Miller [Phys. Rev. A 11, 1417 (1975)] quantitatively fits the data with reasonable thermodynamic and transport parameters. © 1997 The American Physical Society.