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)


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
Issue number8
Publication statusPublished - 2005 Nov
Externally publishedYes


  • 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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