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Micro-plasticity in a fragile model binary glass

  • Atomistic deformation simulations in the nominally elastic regime are performed for a model binary glass with strain rates as low as 10 4 /s (corresponding to 0.01 shear strain per 1 μs). A strain rate dependent elastic softening due to a micro-plasticity is observed, which is mediated by thermally-activated localized structural transformations (LSEs). A closer inspection of the atomic-scale structure indicates the material response is distinctly different for two types of local atomic environments. A system spanning iscosahe- drally coordinated substructure responds purely elastically, whereas the remaining substructure admits both elastic and microplastic evolution. This leads to a heterogeneous internal stress distribution which, upon unloading, results in negative creep and complete residual-strain recovery. A detailed structural analysis in terms of local stress, atomic displacement, and SU(2) local bonding topology shows such mi- croscopic processes can result in large changes inAtomistic deformation simulations in the nominally elastic regime are performed for a model binary glass with strain rates as low as 10 4 /s (corresponding to 0.01 shear strain per 1 μs). A strain rate dependent elastic softening due to a micro-plasticity is observed, which is mediated by thermally-activated localized structural transformations (LSEs). A closer inspection of the atomic-scale structure indicates the material response is distinctly different for two types of local atomic environments. A system spanning iscosahe- drally coordinated substructure responds purely elastically, whereas the remaining substructure admits both elastic and microplastic evolution. This leads to a heterogeneous internal stress distribution which, upon unloading, results in negative creep and complete residual-strain recovery. A detailed structural analysis in terms of local stress, atomic displacement, and SU(2) local bonding topology shows such mi- croscopic processes can result in large changes in local stress and are more likely to occur in geomet- rically frustrated regions characterized by higher free volume and softer elastic stiffness. The thermally- activated LSE activity also mediates structural relaxation, and in this way should be distinguished from stress-driven shear transformation activity which only rejuvenates glass structure. The frequency of LSE activity, and therefore the amount of micro-plasticity, is found to be related to the degree to which the glassy state is relaxed. These insights shed atomistic light onto the structural origins that may govern re- cent experimental observations of significant structural evolution in response to elastic loading protocols.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Robert Maaß, P. Derlet
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Acta Materialia
Jahr der Erstveröffentlichung:2021
Organisationseinheit der BAM:5 Werkstofftechnik
5 Werkstofftechnik / 5.0 Abteilungsleitung und andere
Veröffentlichende Institution:Bundesanstalt für Materialforschung und -prüfung (BAM)
Verlag:Elsevier Ltd.
Jahrgang/Band:209
Erste Seite:116771
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Bulk metallic glasses; Molecular dynamics; Plasticity; Residual strains
Themenfelder/Aktivitätsfelder der BAM:Material
Material / Materialien und Stoffe
DOI:https://doi.org/10.1016/j.actamat.2021.116771
URN:urn:nbn:de:kobv:b43-523782
Verfügbarkeit des Dokuments:Datei für die Öffentlichkeit verfügbar ("Open Access")
Lizenz (Deutsch):License LogoCreative Commons - CC BY - Namensnennung 4.0 International
Datum der Freischaltung:07.04.2021
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:20.05.2021
Schriftenreihen ohne Nummerierung:Wissenschaftliche Artikel der BAM