Structure and morphology of [icosahedral Al62Cu25.5Fe12.5]100−x[decagonal Al70Co15Ni15]x alloys, for x=10∗(0∼3 and 5∼10)

Alloys made from mixtures of Al62Cu25.5Fe12.5 icosahedral quasicrystal (IQC) and Al70Co15Ni15 decagonal quasicrystal (DQC) were studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The transition from IQC to DQC was thus discussed by studying the evolution of their constituent phases in each alloy. Three approximant phases were found as common phases in most of the pseudo-binary alloys: λ-Al13Fe4, β-AlFe and τ3-Al3Ni2. It is found that, with the increment of the DQC content in the alloy, the λ phase changes from Al13Fe4 to Al13Co4 and the τ3 phase changes from Al3Cu2 to Al3Ni2. The formation of these phases were found also to follow the evolution of their corresponding e/a-constant lines in the Al–(Cu,Ni)–(Fe,Co) pseudo-ternary phase diagram. Under this framework, the roles played by the related approximants in the transition process are briefly discussed.