High-temperature stability and faceting of the icosahedral Al—Fe—Cu phase

Thin fragments of dodecahedral particles, extracted from an as-cast Al65Fe15Cu20 alloy ingot, have been studied by transmission electron microscopy. The as-cast state is not icosahedral but trigonal and exhibits a microstructure such that the overall symmetry is pesudo-icosahedral; annealed within the microscope, this microcrystalline state transforms homogeneously into the icosahedral phase, stable until its melting point. During this second transformation (surface melting or sublimation), faceted holes of a dodecahedra] shape were observed to develop within the quasicrystalline phase.