Temperature dependence of the generalized vibrational density of states of Al70Co15Ni15 and Al62Co15Cu20Si3

The temperature dependence of the atomic dynamics of AlCoNi and AlCoCuSi was investigated via the generalized vibrational density of states (GVDOS) using neutron inelastic scattering. With increasing temperature we observe a strong anharmonic softening of the dynamics which is essentially linear with temperature for AlCoNi but shows a step for AlCoCuSi. From the shape of the GVDOS we conclude that in AlCoNi the short range order changes little with temperature while it does change in AlCoCuSi. In the case of AlCoNi the GVDOS measured at 296 K can be nearly quantitatively described by a computer simulation based on a tiling model and ab initio pair potentials for Al and Co.