Study of homogenization treatments of cast 5xxx series ai-mg-mn alloy modified with zn

Abstract

Microstructural changes of DC-cast 5xxx series AI-Mg-Mn alloy modified with Zn addition occurring during the homogenization treatments were studied through the thickness of a rolling ingot. The homogenization treatments included: low temperature annealing at 430 degrees C for 12h and high temperature homogenization at 550 degrees C for 16h. Microstructure evolution was followed by electrical resistivity measurements, optical microscopy, SEM and TEM characterization and microanalysis. During the homogenization, decomposition of the supersaturated solid solution, present in the as-cast state, occurred. Distribution of the precipitates was dictated by segregations and could be related to the partition coefficients of alloying elements. It was found that during the high temperature homogenization not only dissolution processes occurred, but also precipitation of new phases.