Nucleation and growth of deformation twins: A perspective based on the double-cross-slip mechanism of deformation twinning

Deformation twins have been oberved in nanocrystalline (NC) Al synthsized by cryogenic ball-milling and in NC Cu processed by high-pressure torsion under room temperature and at a very low strain rate. They were found formed by partial dislocations emitted from grain boundaries. This paper first reviews experimental evidences on deformation twinning and partial dislocation emissions from grain boundaries, and then discusses recent analytical models on the nucleation and growth of deformation twins. These models are compared with experimental results to establish their validity and limitations.

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Deformation twinning and the role of amino acids and magnesium in calcite hardness from molecular simulation

Physical Chemistry Chemical Physics ◽

10.1039/c5cp03370e ◽

2015 ◽

Vol 17 (31) ◽

pp. 20178-20184 ◽

Cited By ~ 16

Author(s):

A. S. Côté ◽

R. Darkins ◽

D. M. Duffy

Keyword(s):

Molecular Dynamics ◽

Amino Acids ◽

Molecular Simulation ◽

Elastic Properties ◽

Deformation Twinning ◽

Pure Crystal ◽

Classical Molecular Dynamics ◽

Deformation Twins

We employ classical molecular dynamics to calculate elastic properties and to model the nucleation and propagation of deformation twins in calcite, both as a pure crystal and with magnesium and aspartate inclusions.

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Orientation Dependent Strength and Cross-Slip Structure of Ordinary Dislocations in Single Crystal γ-Ti-56A1

MRS Proceedings ◽

10.1557/proc-552-kk1.10.1 ◽

1998 ◽

Vol 552 ◽

Author(s):

Q. Feng ◽

S. H.

Keyword(s):

Single Crystal ◽

High Temperatures ◽

Slip Plane ◽

Forward Direction ◽

Orientation Dependence ◽

Cross Slip ◽

Dislocation Loops ◽

Single Slip ◽

Anomalous Hardening ◽

Double Cross

ABSTRACTThe temperature as well as orientation dependence in anomalous hardening occurs in single crystal Ti-56AI between 673K and 1073K under single slip of ordinary dislocations. The ordinary dislocations (1/2<110]) are gliding not only on (111) plane but also on (110) plane in the temperature range where the anomalous hardening occurs in single crystal Ti-56A1. The TEM study shows that the (110) cross-slip of ordinary dislocations is a double cross-slip in nature in which first, the dislocations cross-slip from the primary (111) slip plane to (110) plane followed by cross-slipping again onto another primary slip plane. This double cross-slip leaves a pair of edge segments 'superjogs' in (110) planes. It appears that these superjogs are immobile in the forward direction and act as pinning points. Furthermore, these pinning points would act as a Frank-Read source for the double cross-slipped dislocations, which generate dislocation loops as well as dislocation dipoles. The pinning structure, multiplane dislocation loops, and dipoles of double cross-slip origin all contribute to anomalous hardening at high temperatures in this material.

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Nucleation and growth of deformation twins in Mo-35 at. % Re alloy

Philosophical Magazine ◽

10.1080/14786437208221027 ◽

1972 ◽

Vol 26 (1) ◽

pp. 161-171 ◽

Cited By ~ 32

Author(s):

S. Mahajan

Keyword(s):

Nucleation And Growth ◽

Deformation Twins

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The Brittle-to-Ductile Transition Behaviour in Fe-Al Single Crystalline Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.409.243 ◽

2011 ◽

Vol 409 ◽

pp. 243-248

Author(s):

Keiki Maeno ◽

Masaki Tanaka ◽

Kenji Higashida ◽

Masahiro Fujikura ◽

Kohsaku Ushioda

Keyword(s):

Brittle Fracture ◽

Low Temperatures ◽

Room Temperature ◽

Tensile Tests ◽

Initiation Site ◽

Deformation Twinning ◽

Brittle To Ductile Transition ◽

Elastic Regime ◽

Deformation Twins ◽

Transition Behaviour

The morphology of deformation twinning, which influences a brittle fracture at low temperatures, was investigated in Fe-8mass%Al. Tensile tests were performed at 129K and room temperature. The specimen tested at room temperature showed yielding and kept deformed by usual slip while the specimen tested at 129K fractured in a brittle manner in an elastic regime with a number of straight markings due to deformation twinning. Detail analysis of those deformation twins suggests that the collision of deformation twinning is the initiation site of the brittle fracture.

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