Elastic Moduli of a Single Quasicrystal of Decagonal Al-Ni-Co: Evidence for Transverse Elastic Isotropy

The single quasicrystal elastic moduli $c_{\mathrm{ij}}$ of decagonal Al-Ni-Co were determined using resonant ultrasound spectroscopy at selected fixed temperatures in the range between 5 and 290 K. Decagonal Al-Ni-Co is found to be transversely elastically isotropic to $(0.02\pm 0.04)\%$. The elastic moduli $c_{\mathrm{ij}}\left(T\right)$ exhibit weak temperature dependences. The elastic Debye temperature ${\Theta }_D^{\mathrm{el}}$ calculated from $c_{\mathrm{ij}}$ measured at 5 K agrees well with the thermodynamic Debye temperature ${\Theta }_D^{\mathrm{th}}$ obtained from a low-temperature specific-heat experiment.