Quasicrystal Structures

Cubic approximants in quasicrystal structures

2014 The regular deviations from the exact icosahedral symmetry, usually observed at the diffraction patterns of quasicrystal alloys, are analyzed. It is shown that shifting, splitting and asymmetric broadening of reflections can be attributed to crystalline phases with the cubic symmetry very close to the icosahedral one (such pseudo-icosahedral cubic approximants may be called the Fibonacci c...

Quasicrystal approximants with novel compositions and structures

We identify several new quasicrystal approximants in alloy systems in which quasicrystals have not been previously reported. Some occur in alloys with large size contrast between the constituent elements, either containing small Boron atoms, or large Ca/Eu atoms, leading to quasicrystal structures quite different from currently known systems where the size contrast is smaller. Another group of ...

Quasicrystal equilibrium state.

Deceptions in Quasicrystal Growth

We discuss a new general phenomenon pertaining to tiling models of quasicrystal growth. It is known that with Penrose tiles no (de-terministic) local matching rules exist which guarantee defect-free tiling for regions of arbitrary large size. We prove that this property holds quite generally: namely, that the emergence of defects in quasicrystal growth is unavoidable for all aperiodic tiling mo...

Quasicrystal-reinforced Mg alloys

The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg-Zn-Y and Mg-Zn-Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + α-Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/m...