Structural State of β-Solid Solution in Quenched Quasicrystal-Forming Alloys of Al₆₁Cu₂₆Fe₁₃

Electron microscopic investigations of the structural state have been carried out for the β(CsCl-type)-phase in the quenched quasicrystal-forming two-phase (ι + β) alloy Al₆₁Cu₂₆Fe₁₃. We conclude that in the vicinity of compositions at which the icosahedral phase (ι) is formed, at deviations from the composition Al₃(Cu,Fe)₂ towards Al(Cu,Fe), the β(CsCl-type)-solid solution has a heterogeneous structure (a state similar to the diffuse incommensurable ω-phase in b.c.c.-solid solutions). This structure includes the β-matrix with fine regions of correlated ω-like displacements which in a certain way are interrelated with the τ₃-short-range order of substitution. It is concluded that the β(CsCl-type)-phase of Al_61—xCu_26+yFe_13—z reveals structural signs typical for electron-stabilized solid solutions, and because of this, the β-phase demonstrates a “dielectric” behavior of its electronic properties. An assumption has been made that the regions with ω-displacements are involved in the structural transformation β-phase → ι-phase.