Influence of Si and Fe on the distribution of intermetallic compounds in twin-roll cast Al–Mn–Zr alloys

The aim of the experiments was to study the influence of Si and Fe on size and formation of secondary phases and recrystallization behavior of Al–Mn–Zr alloys prepared by twin-roll casting (TRC) in the industrial conditions. Microstructure (grain structure, phase composition, particle analysis) of these alloys was characterized during downstream processing. Quantitative particle analysis was carried out on FEG–SEM micrographs at both high and low magnifications. The phases were examined by light metallography, energy dispersive X-ray spectroscopy (EDXS) and by means of electron back-scattering diffraction (EBSD) according to their crystallographic structure. The microstructure at the final gauge was also observed by transmission electron microscope (TEM). A relatively high (0.5 wt.%) Si content and low (0.2 wt.%) Fe content in one of the alloys resulted in balancing of nucleation and dissolution rate for small particles. Hence a higher density of small particles was stable during the downstream processing, and this alloy showed improved recrystallization resistance.

► Influence of Si and Fe on the recrystallization resistance of twin-roll cast alloys.
► Quantitative particle analysis on series of FEG–SEM micrographs.
► Increase of the density of coarse particles in alloy with Fe excess over Si.
► High and almost constant density of fine particles in alloy with Si excess over Fe.
► High recrystallization resistance of alloy with Si excess over Fe.