Growth of ‘Stimulated Crystals” and Rate of Nucleation during Recrystallization of Aluminium

Abstract

In a fundamental paper, Anderson and Mehl¹ deduce from their measurements the rate of nucleation (N) (that is, the number of new grains formed per unit time in unit area) and the rate of growth during recrystallization of aluminium (G). The following remarks deal only with the dependence of these two quantities on the time of recrystallization at constant temperature. They were measured by Anderson and Mehl in very thin sheets (‘two-dimensional’ recrystallization) and also in much thicker sheets (‘three-dimensional’ recrystallization) by determining the percentage of recrystallized material and the number of new grains as a function of the time of heating. Whereas it was found that G was independent of time, in agreement with direct measurements by several investigators of the rate of growth of large crystals in fine-grained material (references in ref. 2, § 91), the remarkable result was obtained that N increased with time, which means that the number of new grains formed per unit surface (or unit volume) of unrecrystallized material per second increased in the course of the recrystallization process.