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Twin-roll casting is an effective and energy-saving method enabling direct preparation of strips of the requested final thickness. However, due to high solidification rates and higher solid solution supersaturation a significantly different microstructure is formed in comparison with conventionally cast alloys. Recently, the Sc and Zr containing aluminum alloys are considered to be new advanced materials for the transportation industry. The influence of Sc and Zr on mechanical properties of twin-roll cast Al-Mg alloy was investigated in the present study. A significant effect of Sc and Zr on hardening of the material after annealing in temperature interval between 250 • C and 400 • C was confirmed. Maximal hardness was obtained after two hours of annealing at 300 • C due to precipitation of a fine dispersion of Sc and Zr containing precipitates. Exposure of the annealed material to higher temperatures results in a partial degradation of mechanical properties due to changes of the strengthening effect of precipitates. However, a partially positive role of remaining precipitates, hindering recrystallization, persists even up to 550 • C.

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The Al-Mg-Sc alloys are used in aerospace and shipbuilding industry due to their good mechanical properties such as corrosion resistance, weldability and possibility for superplastic forming. Addition of Sc with Zr may further lead to enhancement of their performance by precipitation of coherent particles of Al3(Sc,Zr) phase which are known to stabilize the microstructure and hinder the recrystallization. The role of the material processing on the microstructure and mechanical properties evolution was studied by means of transmission electron microscopy, scanning electron microscopy and resistivity measurement. The Al-Mg-Sc-Zr alloy was manufactured by two different manners-conventional casting and twin-roll casting and subjected to deformation by equal-channel angular pressing. The shape and nature of the grains significantly influenced precipitation of β-phase Al3Mg2, which may be detrimental for such kind of materials in the terms of corrosion resistance. The worst properties exhibited the conventionally cast and rolled material with a pancake grain structure where the β-phase particles forms as continuous layer along the (sub)grain boundaries.

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