Abstract
We have measured the specific heat of the icosahedral i-Al84Mn16 quasi-crystal and also of three crystalline compounds with related composition: hexagonal h-Al4Mn and h-Al71Fe19Si10, and cubic c-Al50Mn12Si7. The electron density of states at the Fermi level is high in both i-Al84Mn16 and h-Al4Mn alloys. This result is consistent with recent predictions for icosahedral Al clusters by McHenry et al. The Debye temperature θD is lower in the nonperiodic i-phase, thus revealing a softening of elastic constants.