Solid-state formation of icosahedral quasicrystals at Zn3Mg3Y2/Mg interfaces in a Mg–Zn–Y alloy

• Solid-state formation of quasicrystals was observed in a Mg–Zn–Y alloy.
• The icosahedral quasicrystals were formed upon heating, instead of cooling.
• The icosahedral quasicrystals have specific orientation relationship with W phase.
• Interfaces between the icosahedral quasicrystal and W are epitaxially bonded.

Solid-state formation of Zn6Mg3Y icosahedral quasicrystals was observed at interfaces between Mg and W–Zn3Mg3Y2 crystals in a Mg–Zn–Y alloy by in situ transmission electron microscopy investigations. The quasicrystals were formed at about 593 K which is about 130 K below the peritectic temperature. Thermally driven interdiffusion of atoms across the W/Mg interface firstly produces local regions with Zn:Mg:Y close to 6:3:1 at the surface of W phase particles, where the cuboctahedral packing of atoms in W phase transforms to icosahedral packing through slight rearrangement of atoms, leading to the nucleation and growth of icosahedral clusters. The icosahedral clusters act as nuclei for the growth of icosahedral quasicrystals. Both valence electron concentration and the densest packing of atoms play important roles in the formation of Zn6Mg3Y quasicrystals. Solid-state formation of icosahedral quasicrystals at W/Mg interfaces provide a feasible way to modify the weakly bonded W/Mg interfaces, which is thus believed to be able to improve the magnesium alloy's mechanical properties.

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