scholarly journals A Stress Orientation Analysis Framework for Dislocation Glide in Face-Centred Cubic Metals

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 445 ◽  
Author(s):  
Fernando Daniel León-Cázares ◽  
Catherine Mary Fiona Rae
Keyword(s):  
Slip Plane ◽  
Orientation Dependence ◽  
Slip Systems ◽  
Analysis Framework ◽  
Orientation Analysis ◽  
Dislocation Glide ◽  
Stress Orientation ◽  
Orientation Maps ◽  
Nucleation Mechanisms ◽  
Geometrical Constraints

Plastic deformation in metals is heavily influenced by the loading direction. Studies have explored its effects on multiple mechanisms by analysing individual dislocations, but there is currently no systematic way of rationalising the cooperative behaviour of the different slip systems for arbitrary stress tensors. The current study constitutes the foundation of a new orientation analysis framework for face-centred cubic crystals by introducing “stress orientation maps”, graphical tools to simultaneously analyse the effects of loading orientation on the stress state of the a 2 ⟨ 1 1 ¯ 0 ⟩ { 111 } and a 6 ⟨ 112 ⟩ { 111 } slip systems in a comprehensive, yet intuitive way. Relationships between the Schmid and Escaig stresses are described from geometrical constraints of the slip systems in the crystal structure, linking the dislocation behaviour on a slip plane with the stress tensor via a one parameter description. The case of uniaxial loading along different orientations within the fundamental sector of the unit cell is explored to describe the physical basis, properties and capabilities of this framework. The stress normal to the slip plane is then considered in the analysis via an extension of the Mohr’s circles. The orientation dependence of two twin nucleation mechanisms from the literature are examined as examples of how the stress orientation maps can be used.

Stress Orientation Dependence of Dislocation Glide in Epitaxial Films

1990 ◽  
Vol 202 ◽  
Author(s):  
S. Dakshinamurthy ◽  
K. Rajan
Keyword(s):  
Crystal Orientation ◽  
Stereographic Projection ◽  
Epitaxial Films ◽  
Orientation Dependence ◽  
Stress Axis ◽  
Dislocation Glide ◽  
Stress Orientation ◽  
Slip Transfer

ABSTRACTThe effect of different stresses on the glide of the commonly observed dislocations in epitaxial films is systematically investigated. The possibility of planar dissociation of perfect dislocations and the conditions for their subsequent glide are explored.Slip transfer from one plane to another is affected by the crystal orientation relative to the stress axis. This process is quantitatively analyzed by calculating iso-Schmid factors on a stereographic projection. The results of this model are correlated with those found in the literature.

The Orientation Dependence of Work?Hardening in Crystals of Face-centred Cubic Metals

1960 ◽  
Vol 13 (2) ◽  
pp. 316 ◽  
Author(s):  
LM Clarebrough ◽  
ME Hargreaves
Keyword(s):  
Shear Stress ◽  
Slip Plane ◽  
Work Hardening ◽  
Orientation Dependence ◽  
Slip Systems ◽  
Deformation Bands ◽  
Secondary Slip ◽  
Cubic Metals ◽  
Primary Slip Plane

It is shown that the principal features of the observed orientation dependence of work-hardening can be accounted for in terms of the likelihood of formation. Of Lomer-Cottrell sessile dislocations in two directions in tb" primary slip plane. This is deduced from the known variation of resolved shear stress with orientation, for the possible secondary slip systems, and metallographic observations of slip and deformation bands.

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

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.

scholarly journals Texture analysis of experimentally deformed Black Hills Quartzite

2017 ◽  
Author(s):  
Rüdiger Kilian ◽  
Renée Heilbronner
Keyword(s):  
Black Hills ◽  
Dislocation Creep ◽  
Shear Stresses ◽  
Slip Systems ◽  
Dislocation Glide ◽  
Aspect Ratios ◽  
Deformation Intensity ◽  
Pole Figures ◽  
Three Samples ◽  
Texture Transition

Abstract. The textures of three samples of Black Hills quartzite (BHQ) deformed experimentally in the dislocation creep regime 1, 2 and 3 (according to Hirth and Tullis, 1992) have been analysed by EBSD. All samples were deformed to relatively high strain, within a temperature range of 65° and identical displacement rates and are almost entirely composed of dynamically recrystallized grains. A texture transition from peripheral c-axes in regime 1 to a central c-axis maximum in regime 3 is observed. Separate pole figures are calculated for different grain sizes, aspect ratios and long axis trend (θ) of grains, and high and low levels of intragranular deformation intensity as measured by the grain kernel average misorientation (gKAM). Misorientation relations are analysed for different texture components (named Y- B- R- and σ, with reference to previously published prism, basal, rhomb and σ1 – grains). Results show that regime 1 and 3 correspond to clear end member textures with regime 2 being transitional. Texture strength and the development of a central c-axis maximum from a girdle distribution depends on deformation intensity at the grain scale and on the contribution of dislocation creep which increases towards regime 3. Combined with calculations of resolved shear stresses and misorientation analysis, it becomes clear that the peripheral c-axis maximum in regime 1 is not due to deformation by basal –<a> slip. We interpret the texture transition as a result of different texture forming processes, one being more efficient at high stresses (formation of grains with peripheral c-axes), the other depending on strain (dislocation glide involving prism and rhomb slip systems), and not as a result of a temperature dependent activity of different slip systems.

Effect of Hydrogen on Dislocation Emission from a Crack Tip in Nickel

1992 ◽  
Vol 291 ◽  
Author(s):  
Richard G. Hoagland
Keyword(s):  
Barrier Height ◽  
Slip Plane ◽  
Crack Tip ◽  
Dislocation Motion ◽  
Dislocation Emission ◽  
Intrinsic Resistance ◽  
Dislocation Glide ◽  
Atomic Models ◽  
Work Done

ABSTRACTA method for determining the intrinsic resistance to dislocation emission and glide in atomic models is presented and applied to EAM models of nickel containing a single-ended crack tip. The method is an adaptation of the Peierls approach in which the work done on the glide plane is computed as a function of dislocation position and its derivative is the intrinsic resistance to dislocation motion. The results indicate that there are two parts to the resistance dislocation glide from the crack tip: a distinct barrier to injection of the dislocation from the crack tip and a periodic resistance associated with the lattice. When a hydrogen interstitial is placed on the slip plane near the crack tip the barrier height is reduced but its width is increased.

Shear Banding in Twinned Structures and Their Influence on Brass-Type Texture

2005 ◽  
Vol 495-497 ◽  
pp. 1067-1072
Author(s):  
Henryk Paul ◽  
Adam Morawiec ◽  
Emmanuel Bouzy ◽  
Jean-Jacques Fundenberger ◽  
Andrzej Piątkowski
Keyword(s):  
Electron Microscopy ◽  
Shear Banding ◽  
Pure Copper ◽  
Shear Bands ◽  
Deformation Mode ◽  
Lattice Rotation ◽  
Slip Systems ◽  
Transmission Electron ◽  
Plane Strain Deformation ◽  
Orientation Maps

The local crystallography within shear bands (SB) has been examined in a single crystal of {112}<111> orientation of pure copper deformed at 77K by channel-die compression to strains of about 1. Setting up a system for making high-resolution orientation maps using transmission electron microscopy (TEM) has opened new advantageous circumstances for the analysis of orientation changes within SB. This method with spatial resolution higher than 10nm allows the examination of microstructure images composed of nanoscale subcells forming SB. It has been found that for well-developed shear bands, a crystal lattice rotation about <112> direction tends to dominate and this process is usually accompanied by activation of new slip systems. The present work shows that despite the plane strain deformation mode, the mechanism of lattice rotation within emerging SBs may lead to Goss and Brass texture components.

scholarly journals Strain hardening recovery mediated by coherent precipitates in lightweight steel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sung-Dae Kim ◽  
Seong-Jun Park ◽  
Jae hoon Jang ◽  
Joonoh Moon ◽  
Heon-Young Ha ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Mean Free Path ◽  
Aged Alloy ◽  
Slip Systems ◽  
Multiple Slip ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Planar Dislocation ◽  
Shearing Mechanism ◽  
Strain Hardening Behavior

AbstractWe investigated the effect of κ-carbide precipitates on the strain hardening behavior of aged Fe–Mn-Al-C alloys by microstructure analysis. The κ-carbides-strengthened Fe–Mn-Al-C alloys exhibited a superior strength-ductility balance enabled by the recovery of the strain hardening rate. To understand the relation between the κ-carbides and strain hardening recovery, dislocation gliding in the aged alloys during plastic deformation was analyzed through in situ tensile transmission electron microscopy (TEM). The in situ TEM results confirmed the particle shearing mechanism leads to planar dislocation gliding. During deformation of the 100 h-aged alloy, some gliding dislocations were strongly pinned by the large κ-carbide blocks and were prone to cross-slip, leading to the activation of multiple slip systems. The abrupt decline in the dislocation mean free path was attributed to the activation of multiple slip systems, resulting in the rapid saturation of the strain hardening recovery. It is concluded that the planar dislocation glide and sequential activation of slip systems are key to induce strain hardening recovery in polycrystalline metals. Thus, if a microstructure is designed such that dislocations glide in a planar manner, the strain hardening recovery could be utilized to obtain enhanced mechanical properties of the material.

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