Structural effects on diffusion in metallic glasses: The pressure dependence of Ni diffusion in as-quenched and relaxed Co<sub>42</sub>Zr<sub>58</sub>

Klugkist, P.; Rätzke, Klaus; Faupel, Franz; Roche, P.T; Fielitz, P.; Naundorf, V.

doi:10.1080/095008399176652

Cited by 13 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The activation volumes from both metadynamics and normal MD are self-consistent, and they also agree quantitatively with the experimental data [3]. For example, the activation volume is experimentally determined as V ¼ 0.5U atom for Hf, Au diffusion in Ni 54 Zr 46 [73]; V ¼ (0.35À0.64)U atom for 63 Ni in Zr-Cu-Ni-Ti-Be [74]; and (0.66 ± 0.15)U atom for Ni diffusion in Co 42 Zr 58 [75]. Finally, we note that even though large collective atomic diffusion happens, it is a result of a single triggered atom hopping process.…”

Section: Temperature and Pressure Dependencesupporting

confidence: 81%

A free energy landscape perspective on the nature of collective diffusion in amorphous solids

Wang

Shinzato

et al. 2018

Acta Materialia

View full text Add to dashboard Cite

The nature of collective diffusion in amorphous solids is in strong contrast with diffusion in crystals. However, the atomic-scale mechanism and kinetics of such collective diffusion remains elusive. Here the free energy landscape of collective diffusion triggered by single atom hopping in a prototypical Cu 50 Zr 50 metallic glass is explored with well-tempered metadynamics which significantly expands the observation timescale of diffusion at atomic-scale. We clarify an experimentally suggested collective atomic diffusion mechanism in the deep glassy state. The collective nature is strongly temperature-dependent. It evolves from string-like motion with only several atoms to be large size collective diffusion at high temperature, which can promote the atomic transport upon glass transition temperature. We also clarify the apparent diffusivity is dominated by the highest free energy barrier of atomic diffusion among widely distributed free energy barriers due to the dynamic heterogeneity of metallic glass, which suggests the sequential nature of diffusion is a proper assumption to the metallic glasses with dynamic heterogeneity. The temperature and pressure dependence of diffusion free energy landscape are further quantified with activation entropy, (19.6 ± 2.5)k B , and activation volume, (7.9 ± 3.4) Å 3 , which agree quantitatively with experiments. Laboratory timescale simulations of atomic diffusion brings physical insights into the unique atomic motion mechanism in non-crystalline materials.

show abstract

Section: Temperature and Pressure Dependencesupporting

confidence: 81%

A free energy landscape perspective on the nature of collective diffusion in amorphous solids

Wang

Shinzato

et al. 2018

Acta Materialia

View full text Add to dashboard Cite

show abstract

“…The effect of structure on diffusion manifests itself in a variation of the diffusivity at constant temperature by 3 orders of magnitude (see Fig. 1) and the occurrence of activation volumes close to zero [15] and such of the order of an atomic volume [33]. Our results reported here show that, irrespective of the large variation of the diffusivity and the activation volume, the isotope effect is close to zero in the entire range.…”

supporting

confidence: 56%

Evidence of Highly Collective Co Diffusion in the Whole Stability Range of Co-Zr Glasses

et al. 2000

Self Cite

View full text Add to dashboard Cite

show abstract

“…This conclusion was also drawn from interdiffusion studies on thin amorphous Ni-Zr-layer samples by Tu and Chou (1988). Amorphous Ni-Zr alloys are known to behave very similarly to Co-Zr alloys (Klugkist et al, 1999). These authors observed void formation (opposite to void formation in the classical Kirkendall effect) when both species, the slowly diffusing Zr and the rapidly diffusing Ni, were mobile.…”

Section: Systems With Considerable Pressure Dependencementioning

confidence: 64%

“…In order to prevent contamination, in particular with oxygen, the gas is highly purified, and, frequently, additional gettering is used, e.g., by wrapping the sample into a Zr foil or adding a Zr sponge. Sometimes samples are specially designed with capping layers (Klugkist et al, 1999;Loirat et al, 2000). To avoid changes in the diffusivity due to a systematic temperature drift with increasing pressure, which might be larger than the expected true change of diffusivity caused by the applied pressure, accurate temperature measurement and control within a few K are necessary.…”

Section: A Introductionmentioning

confidence: 99%

Diffusion in Metallic Glasses and Supercooled Melts

Faupel

Rätzke

2005

Diffusion in Condensed Matter

View full text Add to dashboard Cite

Amorphous metallic alloys, also called metallic glasses, are of considerable technological importance. The metastability of these systems, which gives rise to various rearrangement processes at elevated temperatures, calls for an understanding of their diffusional behavior. From the fundamental point of view, these metallic glasses are the paradigm of dense random packing. Since the recent discovery of bulk metallic glasses it has become possible to measure atomic diffusion in the supercooled liquid state and to study the dynamics of the liquid-to-glass transition in metallic systems. In the present article the authors review experimental results and computer simulations on diffusion in metallic glasses and supercooled melts. They consider in detail the experimental techniques, the temperature dependence of diffusion, effects of structural relaxation, the atom-size dependence, the pressure dependence, the isotope effect, diffusion under irradiation, and molecular-dynamics simulations. It is shown that diffusion in metallic glasses is significantly different from diffusion in crystalline metals and involves thermally activated, highly collective atomic processes. These processes appear to be closely related to low-frequency excitations. Similar thermally activated collective processes were also found to mediate diffusion in the supercooled liquid state well above the caloric glass transition temperature. This strongly supports the mode-coupling scenario of the glass transition, which predicts an arrest of liquidlike flow already at a critical temperature well above the caloric glass transition temperature. CONTENTS

show abstract

Structural effects on diffusion in metallic glasses: The pressure dependence of Ni diffusion in as-quenched and relaxed Co₄₂Zr₅₈

Cited by 13 publications

References 0 publications

A free energy landscape perspective on the nature of collective diffusion in amorphous solids

A free energy landscape perspective on the nature of collective diffusion in amorphous solids

Evidence of Highly Collective Co Diffusion in the Whole Stability Range of Co-Zr Glasses

Diffusion in Metallic Glasses and Supercooled Melts

Contact Info

Product

Resources

About

Structural effects on diffusion in metallic glasses: The pressure dependence of Ni diffusion in as-quenched and relaxed Co42Zr58

Cited by 13 publications

References 0 publications

A free energy landscape perspective on the nature of collective diffusion in amorphous solids

A free energy landscape perspective on the nature of collective diffusion in amorphous solids

Evidence of Highly Collective Co Diffusion in the Whole Stability Range of Co-Zr Glasses

Diffusion in Metallic Glasses and Supercooled Melts

Contact Info

Product

Resources

About

Structural effects on diffusion in metallic glasses: The pressure dependence of Ni diffusion in as-quenched and relaxed Co₄₂Zr₅₈