WORK HARDENING IN EASY GLIDE

1967 ◽  
Vol 45 (2) ◽  
pp. 765-775 ◽  
Author(s):  
P. M. Hazzledine
Keyword(s):  
Flow Stress ◽  
Slip Plane ◽  
Edge Dislocation ◽  
Work Hardening ◽  
Slip Line ◽  
Opposite Sign ◽  
Experimental Measurements ◽  
Line Pattern ◽  
Burgers Vector ◽  
Single Slip

A theory of single-slip work hardening is proposed, in which the flow stress is controlled by the stress required for one group of dislocations to pass another group with the same Burgers vector but with opposite sign on a parallel slip plane. The strain and the details of the slip-line pattern are calculated as a function of stress from the known properties of edge-dislocation multipoles. The predictions of the theory are compared with experimental measurements on Mg and are found to be in fair agreement.The theory presented is a highly simplified first version, and various possible developments of it are discussed.

scholarly journals Twinning in Czochralski-Grown 36°-RY LiTaO3 Single Crystals

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1009
Author(s):  
Yutaka Ohno ◽  
Yuta Kubouchi ◽  
Hideto Yoshida ◽  
Toshio Kochiya ◽  
Tomio Kajigaya
Keyword(s):  
Single Crystals ◽  
Slip Plane ◽  
Edge Dislocation ◽  
Lithium Tantalate ◽  
Initiation Site ◽  
The Other ◽  
Burgers Vector ◽  
Partial Dislocations ◽  
Dislocation Arrays ◽  
Extension Direction

The origin of twinning during the Czochralski (CZ) growth of 36°-RY lithium tantalate (LiTaO3) single crystals is examined, and it is shown that lineages composed of dislocation arrays act as an initiation site for twinning. Two types of lineages expand roughly along three different {12¯10} planes and two different {11¯00} planes. The former lineages and some latter lineages are composed of two types of mixed-dislocations with different Burgers vectors, while the other lineages are composed of only one type of edge-dislocation. All the dislocations have the Burgers vector of ⟨12¯10⟩ type with the compression side at the +Z side. Twin lamellae on {101¯2} are generated at a lineage during the CZ growth. We have hypothesized that dislocations in the lineage with b = 1/3⟨12¯10⟩ change their extension direction along a slip plane of {101¯2}, and they dissociate into pairs of partial dislocations with b = 1/6⟨22¯01⟩and 1/6⟨02¯21¯⟩ forming twin lamellae on {101¯2}.

ON THE MECHANISM OF WORK HARDENING IN f.c.c. METALS

1967 ◽  
Vol 45 (2) ◽  
pp. 631-661 ◽  
Author(s):  
Helmut Kronmüller
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Long Range ◽  
Work Hardening ◽  
Slip Line ◽  
Elastic Interaction ◽  
Stress Fields ◽  
Internal Stresses ◽  
Transmission Microscopy ◽  
Magnetic Methods

A review of the methods applied for the investigation of long-range stresses in deformed single crystals is given. The results found by magnetic methods are discussed in some detail; slip-line data and transmission microscopy are mentioned briefly. The effect of internal stresses on the flow stress is discussed and it is shown that the elastic interaction between the primary dislocations determines the flow stress almost completely. Secondary dislocations are found to be incapable of relaxing the stress fields of the primary dislocations appreciably.

Microtexture Development and Flow Stress Saturation during Triaxial Forging of an Al-3Mg-Sc(Zr) Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 793-800
Author(s):  
S. Ringeval ◽  
David Piot ◽  
Julian H. Driver
Keyword(s):  
Flow Stress ◽  
Work Hardening ◽  
Room Temperature ◽  
Specific Work ◽  
Textural Evolution ◽  
Spatially Resolved ◽  
Grain Fragmentation ◽  
New Type ◽  
Grain Coalescence ◽  
Zr Alloy

An Al-3%Mg-0.25%Sc-0.12%Zr alloy was deformed by triaxial forging at 20-400°C up to strains of about 3. A study of its textural evolution reveals the tendency towards three symmetrical variants of a <110><1 10 ><001> component. This experimental observation is supported by a 3D spatially resolved crystal plasticity analysis. Samples strained at room temperature undergo grain fragmentation in the form of fine substructures and relatively weak textures. Conversely, at 300°C and above, more homogeneous intergranular deformation and rotations give rise to stronger textures. This eventually encourages grain coalescence and thus the development of interpenetrating “orientation chains”, creating a new type of microstructure. The influence of this texture development on the specific work hardening behaviour is discussed.

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.

Basal Plane Dislocation Multiplication via the Hopping Frank-Read Source Mechanism and Observations of Prismatic Glide in 4H-SiC

2012 ◽  
Vol 717-720 ◽  
pp. 327-330 ◽  
Author(s):  
Huan Huan Wang ◽  
Sha Yan Byrapa ◽  
F. Wu ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
...  
Keyword(s):  
Shear Stress ◽  
Slip Plane ◽  
Opposite Direction ◽  
Edge Dislocation ◽  
Basal Plane ◽  
Detailed Mechanism ◽  
Slip Planes ◽  
Basal Plane Dislocation ◽  
Edge Dislocations ◽  
Dislocation Multiplication

In this paper, we report on the synchrotron white beam topographic (SWBXT) observation of “hopping” Frank-Read sources in 4H-SiC. A detailed mechanism for this process is presented which involves threading edge dislocations experiencing a double deflection process involving overgrowth by a macrostep (MP) followed by impingement of that macrostep against a step moving in the opposite direction. These processes enable the single-ended Frank-Read sources created by the pinning of the deflected basal plane dislocation segments at the less mobile threading edge dislocation segments to “hop” from one slip plane to other parallel slip planes. We also report on the nucleation of 1/3< >{ } prismatic dislocation half-loops at the hollow cores of micropipes and their glide under thermal shear stress.

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.

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