Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 47: Liquid and Amorphous Metals III

MM 47.4: Vortrag

Freitag, 27. März 2009, 11:00–11:15, IFW A

Localization and delocalization of free volume and stress field during structural relaxation of metallic glasses — Jixiang Fang, Horst Hahn, and •Herbert Gleiter — Forschungszentrum Karlsruhe, Institut für Nanotechnologie, Karlsruhe 76021, Germany

Molecualr dynamics (MD) simulation indicated that a delocalization phenomenon can be happened in the nanoglasses. The atomic structures as well as the density (and hence all structure/density-dependent properties) of nanoglasses may be tuned by controlling the degree of delocalization (by modifying the annealing time and/or annealing temperature). Here, we show another system to quantitively characterize the localization and delocalization (i.e, its generation and annihilation) of the additional free volume which may be introduced by a stress field of crystal/glass interface formed via embedding crystals into metallic glasses. In this model, W/CuZrAl and W/PdNiP crystal/glass system were selected to obtain a maximum thermal residual stress for the samples prepared from the melt spinning process. Finite element analysis (FEA) was used to optimize the volume faction of tungsten into glass and to study the stress field distribution. Differential scanning calorimetry (DSC) was adopted to quantitively calculate the average free volume in glass and its variation as annealing under different conditions. The thermal residual stresses for the samples as-quenched and annealed under various conditions were measured by the in situ heating X-rays diffraction (XRD) techniques. Above structural relaxation processes was studied in atomic scale by MD simulation.