Calculation of homogenization degree in aluminium alloys using the diffusion parameter approximation

Abstract

Homogenization is a thermal treatment consisting of a lot of processes controlled by the diffusion process that reduces the segregation created during casting. As grains form in the ingot, the structure undergoes considerable enrichment of the solute at the edges of the grains and this is lessened during homogenization. Homogenization only affects microsegregation, not macrosegregation: the shell of an ingot, for example, is not made thinner through homogenization. The homogenization degree is usually characterized by the diffusion parameter developed for infinite crystals, however, the diffusion length, the secondary dendrite arm spacing is finite. In this work a model of finite diffusion length has been developed to calculate the diffusion time belonging to a diffusion degree of 95%.