Publications associées à Intrinsic structural transitions of the pyramidal I 〈c+a〉 dislocation in magnesium

The influence of lattice misfit on screw and edge dislocation-controlled solid solution strengthening in Mo-Ti alloys

William Curtin, Carolina Baruffi, You Rao

Mo-Ti alloys form solid solutions over a wide range of compositions, with lattice misfit parameters increasing significantly with titanium content. This indicates a strong increase in the critical stress for edge dislocation motion. Here, we probe the tran ...

SPRINGERNATURE2023

Strengthening mechanisms in dilute and random solid solution high-entropy BCC alloys

Alireza Ghafarollahi

Tuning the mechanical properties of metals, including strength, through adjusting the type and/or concentration of added solute elements, has been recognized as an effective way to design and produce materials with desired or optimized mechanical propertie ...

EPFL2022

Deciphering the interactions between single arm dislocation sources and coherent twin boundary in nickel bi-crystal

Helena Van Swygenhoven

The introduction of a well-controlled population of coherent twin boundaries (CTBs) is an attractive route to improve the strength ductility product in face centered cubic (FCC) metals. However, the elementary mechanisms controlling the interaction between ...

Nature Research2021

Atomic scale investigations of fracture in metal alloys

Eleanor Yi Kei Mak

The demand for metal alloys with superior structural performance in industrial applications continues to increase, as does the need for more-energy efficient materials and methods. Many materials that are otherwise attractive for structural applications ar ...

EPFL2021

Optimization of composition and structure of cemented carbide cutting tools

Samy Adjam

WC-Co cemented carbides are composites, which combine a hard phase consisting of WC grains and a metallic ductile phase as a binder. Their excellent mechanical properties, combining high hardness, toughness and refractory properties, make them excellent ma ...

EPFL2021

Influence of Joule Effect Heating on Recrystallization Phenomena in Inconel 718

Mathijs Pieter van der Meer, Roland Logé

In this article, the Joule effect heating influence on recrystallization phenomena in the Inconel 718 nickel-based superalloy is investigated in details. On the one hand, static recrystallization kinetic studies at 1020 degrees C after cold deformation up ...

SPRINGER2021

Theory of kink migration in dilute BCC alloys

William Curtin, Alireza Ghafarollahi

Plastic deformation in elemental BCC metals and dilute alloys is controlled by the slower of the kink pair nucleation and kink migration processes along screw dislocations. In alloys nucleation is facilitated and migration inhibited, leading to a concentra ...

2021

Brittle faulting of ductile rock induced by pore fluid pressure build‐up

Marie Estelle Solange Violay, Corentin Jean-Marie Rémi Noël, François Xavier Thibault Passelègue

Under upper crustal conditions, deformations are primarily brittle (i.e., localized) and accommodated by frictional mechanisms. At greater depth, deformations are ductile (i.e., distributed) and accommodated by crystal plasticity, diffusion mass transfer o ...

2021

Atomic Scale Investigations into the Origins of Ductility in Mg Alloys

Rasool Ahmad

The industrial applications of Mg, the lightest structural metal, and abundant in Earth's crust, are hampered by its low intrinsic ductility and low fracture toughness at room temperature which is attributed to the underlying less symmetric and plastically ...

EPFL2020

Analysis of double cross-slip of pyramidal I < c plus a > screw dislocations and implications for ductility in Mg alloys

William Curtin, Zhaoxuan Wu, Rasool Ahmad

Solute accelerated cross-slip of pyramidal < c + a > screw dislocations has recently been recognized as a crucial mechanism in enhancing the ductility of solid-solution Mg alloys. In pure Mg, cross-slip is ineffective owing to the energy difference between ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Theory of screw dislocation strengthening in random BCC alloys from dilute to "High-Entropy" alloys

William Curtin, Francesco Maresca

Random body-centered-cubic (BCC) "High Entropy" alloys are a new class of alloys, some having high strength and good ductility at room temperature and some having exceptional high-temperature strength. There are no theories of strengthening of screw disloc ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Mechanistic origin of high strength in refractory BCC high entropy alloys up to 1900K

William Curtin, Francesco Maresca

The body centered cubic (BCC) high entropy alloys (HEAs) MoNbTaW and MoNbTaVW show exceptional strength retention up to 1900K. The mechanistic origin of the retained strength is unknown yet is crucial for finding the best alloys across the immense space of ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Design of Ductile Rare-Earth-Free Magnesium Alloys

William Curtin, Zhaoxuan Wu, Binglun Yin, Rasool Ahmad

Pure Mg has low ductility due to a transition of < c+a > pyramidal dislocations to a sessile basal-oriented structure. Dilute alloying generally improves ductility. Enhancement of pyramidal cross-slip from the lower-energy pyramidal II plane to the higher- ...

SPRINGER INTERNATIONAL PUBLISHING AG2020

Fault Stability Across the Seismogenic Zone

François Xavier Thibault Passelègue

Across the seismogenic zone, the transition from brittle to plastic deformation corresponds to a semibrittle regime where brittle fracturing and plastic flow coexist at high strength conditions. Thorough experimental investigations on brittle-plastic trans ...

AMER GEOPHYSICAL UNION2020

Designing high ductility in magnesium alloys

William Curtin, Zhaoxuan Wu, Binglun Yin, Rasool Ahmad

The thermally activated pyramidal-to-basal (PB) transition of (c + a) dislocations, transforming glissile pyramidal dissociated core structures into sessile basal dissociated ones, lies at the origin of low ductility in pure magnesium (Mg). Solute-accelera ...

PERGAMON-ELSEVIER SCIENCE LTD2019

The mechanics of crack-tip dislocation emission and twinning

Predrag Andric

Dislocation emission from a crack tip is a necessary mechanism for crack tip blunting and toughening. A material is intrinsically ductile under Mode I loading when the critical stress intensity

K_{Ie}

for dislocation emission is lower than the critical s ...

EPFL2019

CHD3 Dissociation on the Kinked Pt(210) Surface: A Comparison of Experiment and Theory

Rainer Beck, Helen Jane Chadwick, Ana Gutiérrez González

To be able to simulate activated heterogeneously catalyzed reactions on the edge and corner sites of nanoparticles, a method for calculating accurate activation barriers for the reactions is required. We have recently demonstrated that a semiempirical spec ...

2019

A new variational line tension model for accurate evaluation of the stress effect on cross-slip energy barrier in face-centered cubic metals

Xiao Zhou, Hui Liu

The present work developed a new variational line tension model (LTM) that accounts for contributions from the local line energy, long-range interaction among dislocation segments, and interplay between dissociated partials. This new LTM has been shown to ...

2019

Automated Multiscale Approach To Predict Self-Diffusion from a Potential Energy Field

Berend Smit, Senja Dominique Barthel, Amber Kashan Mace

For large-scale screening studies there is a need to estimate the diffusion of gas molecules in nanoporous materials more efficiently than (brute force) molecular dynamics. In particular for systems with low diffusion coefficients molecular dynamics can be ...

2019

Dislocation Cross-Slip in Face-Centered Cubic Solid Solution Alloys

Wolfram Georg Nöhring

The mechanical strength of metals depends on their resistance against various microscopic deformation processes. In ductile metals, the most important process is shearing of the crystal lattice by dislocations. One of the fundamental aspects of dislocation ...

EPFL2018