Structural study of decagonal Al ₆₅ Cu ₁₅ Co ₂₀ alloy by anomalous X-ray scattering method

Atomic structures of as-quenched and as-cast Al ₆₅ Cu ₁₅ Co ₂₀ decagonal alloys have been studied by the anomalous X-ray scattering (AXS) method. It is found that basic structural features in the as-quenched alloy are identical to those of the as-cast alloy, although the peaks are slightly sharper in the as-cast alloy. From the differential interference functions, it would be expected that Co atoms are homogeneously distributed in the decagonal phase but Cu atoms are not. Such difference in the atomic sites for Co and Cu has also been observed in the environmental pair distribution functions (PDFs) for Co and Cu. This is contrast to the environmental structures around Fe and Ni in the Al ₇₅ Fe ₁₅ Ni ₁₀ decagonal alloy. Furthermore, it appears that the local atomic structure in the Al ₆₅ Cu ₁₅ Co ₂₀ decagonal alloy might be similar to that in the Al ₁₃ Fe ₄ crystalline compound.