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Atomistic simulations of model bulk metalic glasses: structural and deformation properties

English title Atomistic simulations of model bulk metalic glasses: structural and deformation properties
Applicant Derlet Peter
Number 137871
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Material Sciences
Start/End 01.05.2012 - 30.04.2016
Approved amount 214'439.00
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All Disciplines (2)

Discipline
Material Sciences
Condensed Matter Physics

Keywords (3)

Bulk Metallic Glasses; Structural and Mechanical Properties; Atomistic Simulation

Lay Summary (English)

Lead
Lay summary

Bulk metallic glasses constitute one example of a class of materials generally referred to as amorphous solids. An amorphous solid is special since it is not regarded as an equilibrium phase of matter, as defined by thermodynamics, but rather as a meta-stable structure with a characteristic time-scale which is usually well beyond that of a typical experiment or appropriate material application. Such glassy materials are made by rapid quenching from the melt, a multi-component metallic alloy, to the glass transition temperature where the viscosity rapidly increases and the atomic mobility rapidly decreases many orders of magnitude. Well below the glass transition temperature is the regime of the amorphous solid, a material exhibiting exceptional structural and mechanical properties such as an enhanced elastic deformation regime and a considerably high yield strength whilst being extremely brittle. The underlying deformation mechanism remains a subject of intense international research and the present project investigates those atomic-scale structural transformations that lead to emergent macroscopic material failure, using both static and dynamic atomistic simulation techniques. In particular, energy-landscape exploration algorithms will be used to traverse the structural energy landscape to identify transition pathways, involving collective atomic activity, that allow the system to exit its current structural state. This will be done as a function of both model system type and applied stress.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Local structural excitations in model glass systems under applied load
S. Swayamjyoti, J. F. Löffler, P. M. Derlet (2016), Local structural excitations in model glass systems under applied load, in Phys. Rev. B., 93, 144202.
Local structural excitations in model glasses
Swayamjyoti S. L\"offler J.F. and Derlet P. M, Local structural excitations in model glasses, in Physical Review B.

Collaboration

Group / person Country
Types of collaboration
Science et Ingénierie des Matériaux et Procédés, Institut Polytechnique de Grenoble, France France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Departament de Física Aplicada Escola Politècnica Superior de Castelldefels Universitat Politècnica Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Exchange of personnel
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
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
2015 MRS Fall Meeting Talk given at a conference Thermally Driven Plasticity in Model Amorphous Solids: A Molecular Dynamics Study 01.12.2015 Boston, United States of America Derlet Peter;
Junior Euromat conference held in Lausanne in July 2014. Talk given at a conference Microscopic Structural Excitations in Model Metallic Glass Systems 21.07.2014 EPFL Lausanne, Switzerland Swayamjyoti Soumya;
MRS Fall meeting 2013 Poster Local Structural Excitations in Model Glass Systems 01.12.2013 Boston, United States of America Derlet Peter;
CECAM workshop (From cooperativity in supercooled liquids to plasticity of amorphous solids) Poster Local Structural Excitations in Model Glass Systems 26.06.2013 Zurich ETHZ, Switzerland Swayamjyoti Soumya; Derlet Peter;


Associated projects

Number Title Start Funding scheme
125143 Atomic arrangements in (bulk) metallic glasses and their dependence on thermo-mechanical treatments 01.04.2009 Project funding (Div. I-III)
120258 Atomic scale characterization of shear bands and evaluation of deformation kinetics in bulk metallic glasses and composites 01.04.2008 Project funding (Div. I-III)
165527 Geometrical characterization of atomic structure and evolution in atomistically simulated model bulk metallic glasses 01.09.2016 Project funding (Div. I-III)
129519 Dynamic Behaviour of Artificial Frustrated Spin Systems 01.05.2010 Project funding (Div. I-III)

Abstract

Amorphous solids, such as bulk metallic glasses (BMGs) well below their glass transition temperature, exhibit interesting thermal and mechanical properties which are a direct result of the strong disorder present at the atomic scale. The precise relationship between local atomic disorder and global material properties remains, however, unclear. In the case of mechanical properties, both theory and atomistic simulation have developed the phenomenological concept of the Shear Transformation Zone (STZ), in which a finite number of atoms structurally transform to relieve local stress. Mesoscopic modelling has, in turn, used such STZ models to simulate macroscopic plastic deformation for a broad range of temperatures and stresses, demonstrating that with increasing applied stress collective STZ behaviour eventually occurs resulting in global plastic flow. Atomic-scale knowledge of STZ structure and how they interact with each other, as a function of stress and temperature, is therefore of paramount importance to gaining a fundamental understanding of BMG plasticity. The present proposal intends to investigate these issues by exploiting leading-edge atomistic simulation methods in which a potential energy exploration algorithm is used to identify and catalogue, both individual and collective, STZ activity as a function of local atomic structure, applied stress, and system type for model glass systems. The following questions will be specifically addressed:•What atomic-scale structural features of BMGs influence the STZ length- and energy-scale? •How does this length- and energy-scale change in the presence of an applied stress? •Given a number of identified (well separated) STZs, what is the nature of their interaction? •How might this change as a function of system type?Answers to these questions will help in addressing the question of what features of the atomic scale disorder are important to the macroscopic plastic response of BMGs.This project proposal seeks funding of a PhD student to perform these activities, and represents the beginning of a collaborative effort between the Condensed Matter Theory Group at the Paul Scherrer Institut and the experimental activities undertaken within the Laboratory of Metal Physics and Technology at the Swiss Federal Institute of Technology - ETH Zurich.
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