54881
2022
eng
1
5
14
article
Elsevier B.V.
0
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--
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Internal nucleation tendency and crystal surface energy obtained from bond energies and crystal lattice data
We present an easy-to-apply method to predict structural trends in the internal nucleation tendency of oxide glasses. The approach is based on calculated crystal fracture surface energies derived from easily accessible diatomic bond energy and crystal lattice data. The applicability of the method is demonstrated on literature nucleation data for isochemically crystallizing oxide glasses.
Journal of Non-Crystalline Solids: X
10.1016/j.nocx.2022.100093
2590-1591
urn:nbn:de:kobv:b43-548814
publish
Creative Commons - CC BY - Namensnennung 4.0 International
Christopher Tielemann
Stefan Reinsch
Robert Maaß
J. Deubener
Ralf Müller
eng
uncontrolled
Glass
eng
uncontrolled
Nucleation tendency
eng
uncontrolled
Fracture surface energy
eng
uncontrolled
Crystal lattice
eng
uncontrolled
Bond energy
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
5.6 Glas
Material
Verlagsliteratur
Datei für die Öffentlichkeit verfügbar ("Open Access")
Wissenschaftliche Artikel der BAM
5.0 Abteilungsleitung und andere
Materialdesign
Bundesanstalt für Materialforschung und -prüfung (BAM)
https://opus4.kobv.de/opus4-bam/files/54881/Internal nucleation tendency and crystal surface energy.pdf
54728
2022
eng
1
8
16
131
article
AIP Publishing
1
--
--
--
In situ thermal annealing transmission electron microscopy of irradiation induced Fe nanoparticle precipitation in Fe–Si alloy
The typical experimental conditions inside a transmission electron microscope (TEM), such as ultra-high vacuum, high-energy electron irradiation, and surface effects of ultrathin TEM specimens, can be the origin of unexpected microstructural changes compared with that of bulk material during in situ thermal-annealing experiments. In this paper, we report on the microstructural changes of a Fe–15%Si alloy during in situ TEM annealing, where, in its bulk form, it exhibits an ordering transformation from D03 to B2 at 650 °C. Using a heating-pot type double tilt holder with a proportional–integral–differential control system, we observed the precipitation of α-Fe both at the sample surface and inside the sample. Surface precipitates formed via surface diffusion are markedly large, several tens of nm, whereas precipitates inside the specimen, which are surrounded by Fe-poor regions, reach a maximum size of 20 nm. This unexpected microstructural evolution could be attributed to vacancies on Si sites, which are induced due to high-energy electron irradiation before heating, as well as enhanced thermal diffusion of Fe atoms.
Journal of Applied Physics
10.1063/5.0070471
0021-8979
publish
21.11.2022
Y. Shimada
Yuki Ikeda
K. Yoshida
M. Sato
J. Chen
Y. Du
K. Inoue
Robert Maaß
Y. Nagai
T. Konno
eng
uncontrolled
In situ thermal-annealing experiment
eng
uncontrolled
Microstructural changes of a Fe Si alloy
eng
uncontrolled
Microstructural evolution
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
Material
Verlagsliteratur
Datei im Netzwerk der BAM verfügbar ("Closed Access")
5.0 Abteilungsleitung und andere
Materialdesign
54601
2022
eng
1
8
11
8
article
American Association for the Advancement of Science
Washington, DC
1
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Predicting nonlinear physical aging of glasses from equilibrium relaxation via the material time
The noncrystalline glassy state of matter plays a role in virtually all fields of materials science and offers complementary properties to those of the crystalline counterpart. The caveat of the glassy state is that it is out of equilibrium and therefore exhibits physical aging, i.e., material properties change over time. For half a century, the physical aging of glasses has been known to be described well by the material-time concept, although the existence of a material time has never been directly validated. We do this here by successfully predicting the aging of the molecular glass 4-vinyl-1,3-dioxolan-2-one from its linear relaxation behavior. This establishes the defining property of the material time. Via the fluctuation-dissipation theorem, our results imply that physical aging can be predicted from thermal-equilibrium fluctuation data, which is confirmed by computer simulations of a binary liquid mixture.
Science advances
10.1126/sciadv.abl9809
2375-2548
urn:nbn:de:kobv:b43-546015
publish
06.04.2022
Creative Commons - CC BY - Namensnennung 4.0 International
Birte Riechers
L. Roed
S. Mehri
T. Ingebrigtsen
T. Hecksher
J. Dyre
K. Niss
eng
uncontrolled
Physical aging
eng
uncontrolled
Equilibrium relaxation
eng
uncontrolled
Glass
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
Material
Verlagsliteratur
Datei für die Öffentlichkeit verfügbar ("Open Access")
Wissenschaftliche Artikel der BAM
5.0 Abteilungsleitung und andere
Materialdesign
Bundesanstalt für Materialforschung und -prüfung (BAM)
https://opus4.kobv.de/opus4-bam/files/54601/sciadv.abl9809.pdf
54392
2022
eng
1
9
1
13
article
Nature
1
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--
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Mild-to-wild plastic transition is governed by athermal screw dislocation slip in bcc Nb
Plastic deformation in crystals is mediated by the motion of line defects known as dislocations.
For decades, dislocation activity has been treated as a homogeneous, smooth continuous process. However, it is now recognized that plasticity can be determined by longrange correlated and intermittent collective dislocation processes, known as avalanches. Here we demonstrate in body-centered cubic Nb how the long-range and scale-free dynamics at room temperature are progressively quenched out with decreasing temperature, eventually revealing intermittency with a characteristic length scale that approaches the Burgers Vector itself. Plasticity is shown to be bimodal across the studied temperature regime, with conventional thermally-activated smooth plastic flow (‘mild’) coexisting with sporadic Bursts (‘wild’) controlled by athermal screw dislocation activity, thereby violating the classical Notion of temperature-dependent screw dislocation motion at low temperatures. An abrupt increase of the athermal avalanche component is identified at the critical temperature of the material.
Our results indicate that plasticity at any scale can be understood in terms of the coexistence of these mild and wild modes of deformation, which could help design better alloys by suppressing one of the two modes in desired temperature Windows.
Nature Communications
10.1038/s41467-022-28477-4
urn:nbn:de:kobv:b43-543927
publish
09.03.2022
Creative Commons - CC BY - Namensnennung 4.0 International
Q. Rizzardi
C. McElfresh
G. Sparks
D. Stauffer
J. Marian
Robert Maaß
eng
uncontrolled
Plastic deformation
eng
uncontrolled
Microplastic stress
eng
uncontrolled
Intermittent microplasticity
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
Material
Degradation von Werkstoffen
Verlagsliteratur
Datei für die Öffentlichkeit verfügbar ("Open Access")
Wissenschaftliche Artikel der BAM
5.0 Abteilungsleitung und andere
Bundesanstalt für Materialforschung und -prüfung (BAM)
https://opus4.kobv.de/opus4-bam/files/54392/Rizzardi_et_al-2022-Nature_Communications.pdf
53971
2021
eng
1
8
196
13
article
Elsevier Ltd.
1
--
--
--
Early stages of liquid-metal embrittlement in an advanced high-strength steel
Grain-boundary degradation via liquid-metal embrittlement (LME) is a prominent and long-standing failure process in next generation advanced high-strength steels. Here we reveal, well ahead of the crack tip, the presences of nano-scale grains of intermetallic phases in Zn-infiltrated but uncracked grain boundaries with scanning- and 4D transmission electron microscopy. Instead of the often-reported Znrich Fe-Zn intermetallics, the nano-scale phase in the uncracked infiltrated grain boundaries is identified as the G-phase, and its presence reveals the local enhancement of strain heterogeneities in the grain boundary network. Based on these observations, we argue that intermetallic phase formation is not occurring after cracking and subsequent liquid Zn infiltration but is instead one of the primary nanoscopic drivers for grain-boundary weakening and crack initiation. These findings shift the focus of LME from micro- and meso-scale crack investigations to the very early stages immediately following Zn diffusion, after which secondary phase nucleation and growth emerge as the root-cause for failure.
Materials Today Advances
10.1016/j.mtadv.2021.100196
urn:nbn:de:kobv:b43-539716
2590-0498
publish
30.12.2021
Creative Commons - CC BY - Namensnennung 4.0 International
Yuki Ikeda
R. Yuan
A. Chakraborty
H. Ghassemi-Armaki
J. M. Zuo
Robert Maaß
eng
uncontrolled
Advanced high strength steels
eng
uncontrolled
Liquid metal embrittlement
eng
uncontrolled
Transmission electron microscopy
eng
uncontrolled
4-Dimensional scanning transmission
eng
uncontrolled
electron microscopy
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
Material
Verlagsliteratur
Datei für die Öffentlichkeit verfügbar ("Open Access")
Wissenschaftliche Artikel der BAM
5.0 Abteilungsleitung und andere
Materialdesign
Bundesanstalt für Materialforschung und -prüfung (BAM)
https://opus4.kobv.de/opus4-bam/files/53971/Early stages of liquid-metal embrittlement in an advanced high-strength steel.pdf
54152
2021
eng
1
7
5
article
American Physical Society
College Park, MD
1
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Viscosity and transport in a model fragile metallic glass
How thermally activated structural excitations quantitatively mediate transport and microplasticity in a model binary glass at the microsecond timescale is revealed using atomistic simulation. These local excitations, involving a stringlike sequence of atomic displacements, admit a far-field shear-stress signature and underlie the transport of free-volume and bond geometry. Such transport is found to correspond to the Evolution of a disclination network describing the spatial connectivity of topologically distinct bonding environments, demonstrating the important role of geometrical frustration in both glass structure and its underlying dynamics.
Physical review materials
10.1103/PhysRevMaterials.5.125601
2475-9953
publish
13.01.2022
P. Derlet
H. Bocquet
Robert Maaß
eng
uncontrolled
Metallic glass
eng
uncontrolled
Viscosity
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
Material
Verlagsliteratur
Datei im Netzwerk der BAM verfügbar ("Closed Access")
5.0 Abteilungsleitung und andere
Materialdesign
52903
2021
eng
291
1
bookpart
De Gruyter
0
--
--
--
Crystallographic challenges in corrosion research
High-temperature corrosion is a widespread problem in various industries.
As soon as a hot and reactive gas (CO2, O2, H2O, SO2, NOx, etc.) is in contact with a solid, physico-chemical processes at the surface and interfaces lead to material degradation. The processes are dynamic and controlled by thermodynamic and kinetic boundary conditions. Whether a reaction product is protective or not depends on various factors, such as chemical composition of the solid and the reactive media, surface treatment as well as diffusion and transport paths of cations and anions. Resulting chemical and structural inhomogeneities with the corrosion layers are characterized by off stoichiometry within cationic and anionic sub lattices. The competitive processes can be studied by various techniques of applied crystallography.
This chapter gives an overview on the challenges of chemical-structural Analysis of reaction products by crystallographic methods such as X-ray diffraction and X-ray near-edge structure spectroscopy and scanning electron microscopy electron backscatter diffraction (SEM-EBSD) for corrosion science.
Crystallography in Materials Science
10.1515/9783110674910-009
publish
false
true
Christiane Stephan-Scherb
eng
uncontrolled
High-temperature corrosion
eng
uncontrolled
Oxidation
eng
uncontrolled
Diffraction
eng
uncontrolled
Spectroscopy
eng
uncontrolled
Oxides
Analytische Chemie
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
Material
Degradation von Werkstoffen
Chemie und Prozesstechnik
Verlagsliteratur
Datei im Netzwerk der BAM verfügbar ("Closed Access")
5.0 Abteilungsleitung und andere
53076
2021
eng
137
article
Elsevier Ltd.
1
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--
--
Crystal structure characterization of martensite of Cu–Zn–Al ternary alloy by spherical aberration corrected scanning transmission electron microscopy
The crystal structure of martensite in Cu-27at.%Zn-9.0 at.%Al alloy has been studied by using sphericalaberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and geometrical phase analysis (GPA) to examine possible changes in atomic rearrangements during martensitic transformation of this ternary system. Observation along [100]M zone axis is suitable for examining a chemical order of the martensite, and showed that, despite the non-stoichiometry of the alloy, atomic columns containing
Al atoms are imaged and distinguished from the others. On the other hand, observation along [010]M zone axis directly revealed that the parent and martensitic phases possess L21 and 18R (21) structures, respectively. These observations suggested that the martensite retained the local chemical order of the parent phase without shuffling before and after the transformation. GPA revealed that the interface between the two phases was coherent with tilting of the basal plane approximately 6◦ across the boundary, which makes otherwise large inclination small during the martensitic transformation.
Intermetallics
10.1016/j.intermet.2021.107286
0966-9795
publish
21.09.2021
Yuki Ikeda
M. Nishijima
T. Kiguchi
T. Konno
eng
uncontrolled
Shape-memory alloys
eng
uncontrolled
Martensitic transformation
eng
uncontrolled
Martensitic structure
eng
uncontrolled
Electron microscopy, transmission
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
Material
Verlagsliteratur
Datei im Netzwerk der BAM verfügbar ("Closed Access")
5.0 Abteilungsleitung und andere
Materialdesign
53097
2021
eng
218
article
Elsevier Ltd.
1
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--
--
Flaw-insentive fracture of a micrometer-sized brittle metallic glass
Brittle materials, such as oxide glasses, are usually very sensitive to flaws, giving rise to a macroscopic fracture strength that is much lower than that predicted by theory. The same applies to metallic glasses (MGs), with the important difference that these glasses can exhibit certain plastic strain prior to catas- trophic failure. Here we consider the strongest metallic alloy known, a ternary Co 55 Ta 10 B 35 MG. We show that this macroscopically brittle glass is flaw-insensitive at the micrometer scale. This discovery emerges when testing pre-cracked specimens with self-similar geometries, where the fracture stress does not de- crease with increasing pre-crack size. The fracture toughness of this ultra-strong glassy alloy is further shown to increase with increasing sample size. Both these findings deviate from our classical under- standing of fracture mechanics, and are attributed to a transition from toughness-controlled to strength- controlled fracture below a critical sample size.
Acta Materialia
10.1016/j.actamat.2021.117219
publish
28.10.2021
R. Qu
Robert Maaß
Z. Liu
D. Tönnies
L. Tian
R. Ritchie
Z. Zhang
A. Volkert
eng
uncontrolled
Metallic glass
eng
uncontrolled
Fracture toughness
eng
uncontrolled
Size effect
eng
uncontrolled
Small-scale
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
Material
Verlagsliteratur
Datei im Netzwerk der BAM verfügbar ("Closed Access")
5.0 Abteilungsleitung und andere
Materialdesign
52042
2020
eng
lecture
0
--
--
--
Monitoring additive manufacturing processes by using NDT methods
In this presentation we discuss the online monitoring of metallic AM parts produced by the Laser Powder Bed Fusion (LPBF) process by using optical, thermographic and electromagnetic methods. In a first approach we present the detection of defects generated during the process and discuss how to improve these methods for the optimization of design and production of metallic AM parts.
ABENDI - Workshop
Online meeting
19.11.2020
publish
false
true
0
Pedro Dolabella Portella
Alexander Ulbricht
Alexander Evans
Simon Altenburg
Henrik Ehlers
Kai Hilgenberg
Gunther Mohr
deu
uncontrolled
Additive Fertigung
Ingenieurwissenschaften und zugeordnete Tätigkeiten
5 Werkstofftechnik
8 Zerstörungsfreie Prüfung
8.4 Akustische und elektromagnetische Verfahren
8.5 Röntgenbildgebung
9 Komponentensicherheit
Material
Datei im Netzwerk der BAM verfügbar ("Closed Access")
Präsentation
5.0 Abteilungsleitung und andere
8.0 Abteilungsleitung und andere
9.6 Additive Fertigung metallischer Komponenten
Additive Fertigung