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Journal of Materials Science

, Volume 42, Issue 24, pp 10014–10022 | Cite as

High temperature phase stabilized microstructure in Mg–Zn–Sn alloys with Y and Sb additions

  • Anton Gorny
  • Menahem Bamberger
  • Alexander KatsmanEmail author
Article

Abstract

Mg–Zn–Sn alloys exhibit poor structural stability at elevated temperatures that restricts utilization of these alloys. Small additions of alloying elements forming high temperature phases (HTP) were used to improve the structural stability of the Mg–Zn–Sn alloy. The main goal of this work was to investigate the microstructure evolution of the Mg–Zn–Sn-alloy with additions of Y and Sb during a wide scope of heat treatments, and to elucidate peculiarities of an HTP-stabilized microstructure. In order to clarify the substructure features and phase precipitation after each step of the heat treatment, XRD, TEM, SEM and EDS analyses were applied. It was found that in the dendrite structure formed during solidification, HTP-particles are concentrated in the inter-dendrite regions. Solution treatment of the as-cast structure at 440 °C for 96 h lead to the formation of α-Mg grains of 50–80 μm in diameter with a characteristic substructure. The presence of HTP-particles prevented dislocation recovery and movement of dislocation walls during solution treatment, and by this way restricted annihilation of grain boundaries between dendrites of close orientation, and lead to the formation of a substructure with sub-grains of 20–30 μm. The sub-grain boundaries are pinned by HTP-particles and are strengthened by the MgZn2 and Mg2Sn binary precipitates during aging. Precipitate depleted zones formed near grain- and sub-grain boundaries during aging were bordered by a “crust” of enlarged binary particles. Such pinned sub-grain microstructure provides a high structural stability of the alloys at elevated temperatures.

Keywords

Solution Treatment Precipitation Hardening High Temperature Phase HFC134A Solution Treated Alloy 

Notes

Acknowledgements

The study was partially supported by the Fund for the Promotion of Research at the Technion. The foundation is acknowledged for its support.

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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Anton Gorny
    • 1
  • Menahem Bamberger
    • 1
  • Alexander Katsman
    • 1
    Email author
  1. 1.Department of Materials EngineeringTechnion—Israel Institute of TechnologyHaifaIsrael

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