Impact of chromium on the microchemistry evolution during solidification and homogenization of the Al-Mg alloy AA 5052

The materials properties of non-heat treatable 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 physical properties like thermal or electrical conductivity and on mechanical properties including strength and formability of Al alloys. The purpose of the present work is to understand the evolution of microstructure and microchemistry during homogenization of the Cr-containing Al-Mg alloy AA 5052 (AlMg2.5) in comparison with the more widespread Mn-bearing alloy variants. The evolution of the particle state during solidification and subsequent homogenization annealing is tracked with a variety of experimental characterization methods and simulated with microchemistry models to analyse the changes in solute level and precipitation.