The detection of submicroscopic lattice defects in aluminium utilizing a vacancy supersaturation

1969 ◽  
Vol 314 (1516) ◽  
pp. 129-141 ◽  
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Lattice Defects ◽  
Supersaturated Solution ◽  
Dislocation Loops ◽  
Single Slip ◽  
Quench Temperature ◽  
Decoration Technique

The conditions under which submicroscopic defects can be revealed due to decoration by the precipitation of vacant lattice sites from a supersaturated solution have been investigated in aluminium. It is shown that quench temperature, specimen purity and other conditions have to be so chosen that the nucleation of self-sinks is minimized while an adequate vacancy supersaturation is maintained. The conditions for the optimum visibility of defects revealed in this way have been studied primarily by observing the variation in the density of rows of dislocation loops along <110> directions. This decoration technique has been used in quenched single crystals deformed in single slip to show that these rows and also narrow faulted dislocation dipoles with their long axes in the <110> direction form along the specific <110> direction predicted from a hypothesis involving the dragging of a jog by a moving screw dislocation.

Dislocation Structure in Single Crystal L1o Type Ti-Al-V Compound

1990 ◽  
Vol 213 ◽  
Author(s):  
Y.D. Hahn ◽  
Z.X. Li ◽  
S.H. Whang ◽  
T. Kawabata
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
High Temperatures ◽  
Dislocation Structure ◽  
The Other ◽  
Dislocation Loops ◽  
Single Slip ◽  
Pile Up ◽  
Favorable Configuration ◽  
Dipole Form

ABSTRACTSingle Crystals of L1o type Ti44Al54V2 alloy were deformed at high temperatures and various orientations. The dislocations thus produced by single slip were studied by TEM. 1/2<110] dislocations produced at 1073 K consist of dislocation loops and curled dislocations with spiral segments, which is in agreement with those shown in the polycrystalline Ti-Al-V, and -Nb alloys deformed under the same conditions. The normal dislocations produced at 873 K pile up in groups, each of which contains several straight dislocations with a screw character. On the other hand, the majority of superdislocations produced at 873 K were found in a dipole form, indicating that the dipole is a favorable configuration at this temperature.

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

The yield strength anomaly of single-slip-oriented Fe–Al single crystals

2007 ◽  
Vol 15 (2) ◽  
pp. 103-107 ◽  
Author(s):  
D. Wu ◽  
I. Baker ◽  
P.R. Munroe ◽  
E.P. George
Keyword(s):  
Yield Strength ◽  
Single Crystals ◽  
Single Slip

Surface film softening of iron single crystals oriented for single slip

1977 ◽  
Vol 39 (2) ◽  
pp. 491-498 ◽  
Author(s):  
K. Kojima ◽  
M. Meshii
Keyword(s):  
Single Crystals ◽  
Surface Film ◽  
Single Slip

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.

LATTICE DEFECTS IN DIACETYLENE SINGLE CRYSTALS

1990 ◽  
pp. 1653-1658 ◽  
Author(s):  
Kunihide IZUMI ◽  
Minoru KONDO ◽  
Mitsuyoshi MATSUSHITA ◽  
Akio ISHIZAWA
Keyword(s):  
Single Crystals ◽  
Lattice Defects
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