Structure and electrical transport properties of Al-Cu-Cr quasicrystals

Abstract

Transport properties of quasicrystals in rapidly solidified as well as heat-treated Al₆₅Cu₂₀Cr₁₅ alloys were studied over a wide temperature range as a function of structure and microstructure. The characterization was done using x-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. Particular attention was paid to primitive to face-centered quasicrystalline transformation which occurs on annealing and the effect of microstructures on the transport behavior. The temperature dependence of resistivity is found to depend crucially on the microstructure of the alloy. Further, ordering enhances the negative temperature coefficient of resistivity. The low-temperature (T≤ 25 K) resistivity of Al₆₅Cu₂₀Cr₁₅ has been compared with that of Al_63.5Cu_24.5Fe₁₂ alloy. In this region ρ(T) can be well described by a √T contribution arising from electron-electron interaction. We discuss our results in view of current theories.