Simplest model for calculation of isothermal kinetics of the nucleation-and-growth type phase separation in the course of one-step heat treatment

摘要: The simplest model is proposed for calculating kinetics of phase separation performed isothermally after cooling the homogeneous melt to a temp. at which nucleation, growth, and Ostwald ripening of particles of a new phase are possible. Nucleation of particles and their growth occur at the initial stage of heat treatment. The notion of zones depleted of the precipitating component is introduced where nucleation of new particles is impossible. On this basis, the kinetics of nucleation and growth of particles in a supersaturated solution are theoretically described, the initial conditions for calculating the kinetics of Ostwald ripening are stated, and calculations are carried out. Author determines that three approx linear portions with slopes of 1/2 (nucleation-growth stage), 0 (transition period to the Ostwald ripening), and 1/3 (steady-state Ostwald ripening) can be distinguished in the log-log curve of the mean radius vs time …