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Geometrical characterization of atomic structure and evolution in atomistically simulated model bulk metallic glasses

English title Geometrical characterization of atomic structure and evolution in atomistically simulated model bulk metallic glasses
Applicant Derlet Peter
Number 165527
Funding scheme Project funding
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Material Sciences
Start/End 01.09.2016 - 30.11.2019
Approved amount 172'008.00
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All Disciplines (2)

Discipline
Material Sciences
Condensed Matter Physics

Keywords (7)

Plasticity; Simulation; Metal; Glasses; Theory; Disorder; Yield

Lay Summary (German)

Lead
Geometrische Charakterisierung der Atomstruktur und Evolution in atomistisch simulierten Modellmetallgläsern
Lay summary
Das amorphe feste oder strukturelle Glas enthält keine Langstreckenordnung und daher ist es schwierig, seine strukturelle Entwicklung zu klassifizieren, wenn das Material plastisch verformt wird. Das vorliegende Projekt versucht, eine solche Klassifizierung hinsichtlich der Konnektivität von verzerrten und defekten ikosaedrischen lokalen atomaren Umgebungen durchzuführen. Dies wird für computergenerierte atomistische Proben durchgeführt. Diese Arbeiten zielen darauf ab, ein mikroskopisches Klassifizierungsschema zu entwickeln, durch das die atomare Plastizität systematisch untersucht werden kann, was grundlegende Einblicke in die bemerkenswerten mechanischen Eigenschaften dieser unausgewogenen Materialien ermöglicht.
Direct link to Lay Summary Last update: 28.12.2016

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Emergent structural length scales in a model binary glass - The micro-second molecular dynamics time-scale regime
Derlet P.M., Maaß R. (2019), Emergent structural length scales in a model binary glass - The micro-second molecular dynamics time-scale regime, in Journal of Alloys and Compounds, 153209-153209.

Collaboration

Group / person Country
Types of collaboration
Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, U United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Laboratory of Metal Physics and Technology at the Swiss Federal Institute of Technology - ETH Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Associated projects

Number Title Start Funding scheme
137871 Atomistic simulations of model bulk metalic glasses: structural and deformation properties 01.05.2012 Project funding
153103 Shear-band dynamics in bulk metallic glasses and atomic scale study of shear bands 01.04.2014 Project funding
155917 Exploring Artificial Spin Systems in Space and Time 01.04.2015 Project funding

Abstract

Bulk metallic glasses (BMGs) exhibit extraordinary elastic strain limits and a high tensile yield stress whose reproducibility is comparable to industrially relevant steels. Because their ductility is generally limited, a fundamental understanding of the underlying plastic deformation mechanisms will be essential for the development of commercially useful BMGs. Unlike crystalline solids, in which line defects such as dislocations can quantitatively describe the mechanical properties, most theories of BMG deformation rely on a spatially localized plastic mechanism. Such a picture has been supported by extensive high-strain rate molecular dynamics simulations. A more recent atomistic simulation approach, which involves exploring the glassy potential energy landscape (PEL) under zero or finite loading conditions, confirms the existence of such local structural excitations (LSEs). In a currently funded SNF proposal, this method has been used to characterize the atomic scale environment and structure of such LSEs, finding that they exist throughout the material with their position and structure correlating only weakly with local atomic quantities such as free volume, atomic volume, coordination, and local elastic stiffness.How such localized plasticity leads collectively to global failure is a contemporary topic of research, and it is the goal of the current proposal to extend the above work to the regime of collective LSE activity using a a mathematical framework based on both icosahedral local and medium range order which can describe the amorphous solid in a complete and consistent way. Indeed, by recasting the BMG structure in terms of a network-packing of defected icosahedra, the concept of topological line defects can be then applied. It is the central goal of the present proposal to use such a mathematical description to characterize computer generated model BMG structures both in the as-quenched and plastically deformed state. This latter aspect will be done using a new PEL-based adaptable kinetic Monte Carlo algorithm which allows for the study of plastic deformation at experimentally realizable strain rates.The current proposal therefore seeks a follow up of the SNF project (200021_137871) (who's thesis defence is scheduled for April 2016) and thus funding for a new Ph.D. student to perform these activities. This work represents part of an ongoing collaborative effort between the Condensed Matter Theory group at the Paul Scherrer Institute and the Laboratory of Metal Physics and Technology at ETH Zurich.
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