Strengthening in magnesium alloys by icosahedral phase

Alok Singh, M. Watanabe, A. Kato, A. P. Tsai

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)

    Abstract

    Strengthening effects of quasicrystalline icosahedral phase has been studied in two alloys Mg95Zn4.2Y0.8 and Mg 92.5Zn6.5Y extruded at 250 and 400 °C. The quasicrystal particles are facetted and show definite orientation relationships with the matrix. Due to its high symmetry and quasiperiodicity, the icosahedral phase can form strong interfaces with the matrix in various orientations. The icosahedral phase particles have a strong pinning effect on the grain boundaries, which stabilizes grain size. The icosahedral particles are resistant to coarsening, and remain hard at higher temperatures, imparting good strength with ductility at 200 °C. Very few deformation structures such as high dislocation density and twins are observed after extrusion or tensile tests. Dislocations commonly observed are c-type. Due to the stability of microstructure, various post-extrusion treatments are possible. In the Mg 92.5Zn6.5Y alloy upon annealing at 400 °C the icosahedral phase transforms to a hexagonal Mg25Zn58Y 17 phase. The icosahedral phase then reprecipitates on its interface, forming a nano-composite. Effects of microstructural features on the deformation behavior are described.

    Original languageEnglish
    Pages (from-to)895-901
    Number of pages7
    JournalScience and Technology of Advanced Materials
    Volume6
    Issue number8
    DOIs
    Publication statusPublished - 2005 Nov

    Keywords

    • Extrusion
    • Heat treatment
    • Icosahedral phase
    • Magnesium alloys
    • Microstructure
    • Quasicrystal
    • Tensile strength
    • Transmission electron microscopy

    ASJC Scopus subject areas

    • Materials Science(all)

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