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Energetics of dislocation transformations in hcp metals

Related publications (31)

On the structure of (111) twist grain boundaries in diamond: atomistic simulations with Tersoff-type interatomic potentials

In nanocrystalline diamond thin films, the high grain boundary density and the associated grain boundary properties may dominate the overall material behavior. In the present work, we systematically investigate (111) twist grain boundaries in diamond carbo ...

PERGAMON-ELSEVIER SCIENCE LTD2021

{10(1)over-bar2} twinning mechanism during in situ micro-tensile loading of pure Mg: Role of basal slip and twin-twin interactions

Johann Michler, Amit Sharma, Daniele Casari, Roland Logé, Xavier Maeder, Nicolò Maria Della Ventura

An SEM in situ uniaxial tensile testing setup allowing HR-EBSD acquisition during deformation was used to study the extension twinning mechanism in magnesium(Mg) at the micron scale. Structures were fabricated with two different crystal orientations, respe ...

2021

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

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

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

Theory of double-kink nucleation in dilute BCC alloys

William Curtin, Alireza Ghafarollahi

Yielding in pure BCC metals and dilute substitutional alloys occurs by double-kink nucleation and propagation along screw dislocations. At low temperatures, the yield stress is controlled by double-kink nucleation. Here, an analytical statistical model is ...

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

Solute-strengthening in elastically anisotropic fcc alloys

William Curtin, Céline Varvenne, Shankha Nag

Dislocation motion through a random alloy is impeded by its interactions with the compositional fluctuations intrinsic to the alloy, leading to strengthening. A recent theory predicts the strengthening as a function of the solute-dislocation interaction en ...

IOP PUBLISHING LTD2020

Statistical nature of the incipient plasticity in amorphous alloys

Shankha Nag

Statistical analyses of the first pop-in stress data, obtained by spherical tip-nanoindentation experiments on different metallic glasses (MGs) with tip radius, R-i, loading rate, (P) over dot, and structural state of the glass as experimental variables, s ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Triplet grain growth in a-texture polycrystalline ZnO thin films

Arthur Brian Aebersold, Cécile Hébert, Duncan Thomas Lindsay Alexander

A growth of grain triplets is identified in vapor deposited, a-texture polycrystalline zinc oxide thin films, using a combination of transmission electron microscopy-based automated crystal orientation mapping and high-resolution imaging. Each triplet cons ...

2020

Concurrent multiscale modeling and theory of solute-strengthening for dilute and complex concentrated alloys

Shankha Nag

Under common processing conditions, both dilute and complex concentrated alloys are often realized as random alloys, with no correlation in the occupancy of lattice sites by the constituent atom types. The current thesis primary addresses two problems in r ...

EPFL2020