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Precipitation- and stress-influenced coarsening in Mg-based Mg–Zn–Sn–Y and Mg–Zn–Sn–Sb alloys

Published online by Cambridge University Press:  31 January 2011

Anton Gorny  and
Alexander Katsman
Anton Gorny
Affiliation:
Department of Materials Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
Alexander Katsman*
Affiliation:
Department of Materials Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Extensive experimental research work has been carried out to investigate precipitation peculiarities in Mg–Zn–Sn-based alloys during aging at different temperatures. This in-depth research was conducted on Mg–4.4wt%Zn–4.0wt%Sn–0.6wt%Y and Mg–4.4wt%Zn–4.4wt%Sn–1.1wt%Sb using x-ray diffraction (XRD), transmission electron microscopy (TEM) including high-resolution TEM, and scanning electron microscopy (SEM) equipped with an energy-dispersive x-ray spectrometer (EDS). It was found that, first, a hexagonal close-packed (hcp)-MgZn2 phase nucleates and grows in the form of needles having coherent interphase boundaries with α-Mg matrix. Then the face-centered cubic (fcc)-Mg2Sn-phase nucleates heterogeneously, mainly at the tips of MgZn2 needles. A very certain mutual orientation of crystal lattices of MgZn2, Mg2Sn, and α-Mg matrix was revealed. The orientation of Mg2Sn precipitates is perpendicular to that of MgZn2 needles. They grow in the form of plates parallel to the basal planes of α-Mg matrix. Two-phase T-like particles are very typical of alloys aged for 1 to 16 days at 175 to 225 °C. The width/length ratio of MgZn2 needles inside T-like particles differs substantially from that found in single needles. The elastic/surface energy balance of needles and its influence on the morphology and coarsening behavior has been analyzed.

Keywords

MgSecond phasesStress/strain relationship
Type
Articles
Information
Journal of Materials Research , Volume 23 , Issue 5 , May 2008 , pp. 1228 - 1236
Copyright
Copyright © Materials Research Society 2008

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References

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