Electronic properties of stable icosahedral alloys

Abstract

We report specific-heat and resistivity results on icosahedral (i) Ga-Mg-Zn, Al-Cu-Fe, and Al-Cu-V alloys. The electronic densities of states at the Fermi level obtained for the stable i phases of Ga-Mg-Zn and Al-Cu-Fe are substantially less than those found in metastable i phases (Al-Cu-V, Al-Cu-Mg, and Al-Mg-Zn), as small as one-sixth of their free-electron values. Implications for the structural stability of i phases will be discussed. Magnetic-susceptibility and specific-heat measurements on Al-Cu-Fe i phases prepared by rapid quenching and from annealing of the conventionally cast sample show an increased magnetic behavior in the melt-spun sample with respect to the annealed sample. Also, similar to earlier results on Al-Cu-Li i alloys, the Debye temperature of the melt-spun sample is found to be reduced in comparison with the annealed one. These differences in physical properties are attributed to structural differences in the samples. The electronic diffusivities in the stable i phases of Ga-Mg-Zn and Al-Cu-Li are an order of magnitude greater than those observed in previously reported icosahedral alloys, suggesting that the transport properties of some i phases resemble those of crystalline, rather than glassy, alloys.