Ordering Processes inCu3Au

Data are reported which describe the isothermal time rate of change of electrical resistivity in a specimen of ${\mathrm{Cu}}_3$Au following a quench from a temperature above the critical temperature (393°C) to one below it. The experimental arrangements permit observation within one minute after the initiation of the quench. At quench temperatures above 364°C the resistivity rises and then decreases, at first rapidly and then more slowly. The initial rate of fall increases as the quench temperature is lowered. Below 364°C the early rise is absent and the rate of fall decreases with decreasing temperature. The several phenomena are consistent with the hypothesis that the processes involved are the formation, by statistical fluctuation, of stable antiphase nuclei of order in the disordered matrix, the growth of these nuclei, and the coalescence of the resultant antiphase domains. An approximate quantitative theory is developed. Measurements of the isothermal time rate of change of resistivity in an annealed specimen following sudden change of temperature below the critical temperature are in accord with the kinetic theory recently proposed by Jerome Rothstein.