Development of intermetallic particles during solidification and homogenization of two AA 5xxx series Al-Mg alloys with different Mg contents

The materials properties of Al-alloys are controlled by the added alloying elements and the processing conditions through the resulting materials microstructure. An important aspect upon description of the microstructure is the constitution of the material in terms of alloying elements in solid solution and, in turn, volume, size, morphology and species of second-phase particles. These constitutional characteristics, conveniently summarized as microchemistry, have an impact on both physical and mechanical materials properties of non-heat treatable Al-alloys. In the present article we summarize the phase selection upon solidification and the changes in microchemistry during subsequent homogenization annealing during industrial processing of two Al-Mg alloys, AA 5754 (AlMg3) and AA 5182 (AlMg4.5Mn0.4), which are mainly differentiated by their Mg content. The evolution of the particle state during solidification and subsequent homogenization is tracked with a variety of experimental characterization methods and simulated with microchemistry models to analyse the changes in solute level and precipitation.