Atomic dynamics of rapidly quenched and annealed nanocrystalline Ni 89Hf 11

Abstract

We investigated the vibrational behaviour of rapidly quenched and annealed nanocrystalline Ni 89Hf 11 by means of inelastic neutron scattering. From the time-of-flight spectra we determined the generalized vibrational density of states (GVDOS). Using this we calculated the lattice part of the heat capacity. The frequency distribution shows three significant results: First, in reference to the coarser-grained material, the as-quenched nanocrystalline materials show a more enhanced GVDOS at low energies than the annealed ones with almost the same average crystal size. Second, the enhancement is larger the smaller the grain size. Additionally, the energy bands are broadened in case of nanostructured samples.