Crystallographic relationship of orthorhombic φ-Al5Mg11Zn4 phase to icosahedral quasicrystalline phase

The orthorhombic φ-Al5Mg11Zn4 phase is known to be related to quasicrystalline phases, but the exact relationship has not been shown yet. In this study, the relationship of this phase to the icosahedral quasicrystalline phase is explored through analysis of the electron diffraction patterns. It is shown that icosahedral coordinations in three orientations occur in the unit cell – one with three mutually perpendicular twofold axes along 〈1 0 0〉 of the unit cell, and two with a twofold axis along [1 0 0] and a fivefold along [0 0 1]. In this, this phase is similar to aluminum and zinc based hexagonal phases which are related to quasicrystals.

Research highlights
► Electron diffraction patterns from the φ-Al5Mg11Zn4 phase have been recorded.
► Electron diffraction intensities are studied to relate to icosahedral phase.
► It is interpreted that the unit cell contains three icosahedral coordinations.
► This structure is similar to hexagonal phases related to quasicrystalline phases.