INTERNAL-FRICTION, THERMAL AND STRUCTURAL-ANALYSIS OF NANOCRYSTALLINEALUMINUM

Elastic energy dissipation and dynamic elasticity modulus measurements were performed on nanocrystalline aluminium obtained by mechanical at trition and cold consolidation. Information has so far been obtained o n the structural stability of the specimens with different grain sizes and defect contents. The anelasticity spectra from specimens where th e ultimate grain size was reached (20 nm) show a well-defined relaxati on process with an activation energy of 0.8+/-0.1 eV. Differential sca nning calorimetry and transmission electron microscopy observations co nfirmed the defect density dependence and behaviour of the anelastic s pectra.