Homogenization of primary microsegregation

Abstract

The homogenization kinetics of a segregated binary alloy have been studied using electron probe microanalysis after annealing for various times at several temperatures. The concentration and number of microsegregation nodes are quantitatively examined in detail and compared with the evolution of the whole solidification substructure revealed by X-ray images and metallography. The comparison leads to the conclusion that nodes are representative of all solidification substructure and can be taken as a characteristic. The combined study also shows that nodes dissolve in two stages, starting preferentially along cell walls and continuing later in a more uniform fashion. However, a single activation energy near that for bulk diffusion is obtained for the whole process, showing that the homogenization is a collective process and volume diffusion limited.