The mechanism of L12 phase precipitation, microstructure and tensile properties of Al-Mg-Er-Zr alloy

Erbium (Er) is a promising element to replace expensive Scandium (Sc) to improve the mechanical strength of aluminum-based alloys due to the formation of nanoscale dispersoids. However, the effect of Er on precipitation behavior and properties of such alloys is not fully investigated. The paper stud...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2019-01, Vol.744, p.195-205
Main Authors: Mochugovskiy, Andrey G., Mikhaylovskaya, Anastasia V., Tabachkova, Natalya Yu, Portnoy, Vladimir K.
Format: Article
Language:English
Subjects:
Alloys
Aluminum
Aluminum base alloys
Dislocations
Dispersions
Dispersoids
Erbium
Grain boundaries
Heat treating
Heterogeneous nucleation
Magnesium
Mechanical properties
Precipitates
Precipitation
Scandium
Superplasticity
Tensile properties
Thermomechanical treatment
Zirconium base alloys
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Summary:Erbium (Er) is a promising element to replace expensive Scandium (Sc) to improve the mechanical strength of aluminum-based alloys due to the formation of nanoscale dispersoids. However, the effect of Er on precipitation behavior and properties of such alloys is not fully investigated. The paper studied the Er effect on precipitation kinetics of the L12 structured phase by hardness measurements and electron microscopy techniques. Compact continuously-formed dispersoids, which contained similar Zirconium (Zr) and Er concentrations, nucleated homogeneously in a grain body and heterogeneously on dislocations and grain boundaries. Fan-shaped aggregations of the L12 structured Zr-rich Al3(Er,Zr) phase discontinuously precipitated near the grain boundaries. It was found that a two-stage treatment mode provided a maximum hardening effect due to high density of continuously-formed precipitates. The effect of Er and the annealing regimes on the precipitation behavior of the Al-3Mg-0.25Er-0.25Zr alloy were discussed. Mechanical properties, corrosion behavior, and superplasticity of the sheets exposed to simple thermo-mechanical treatments were studied.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2018.11.135