Interactions between Lattice Dislocations and Interfaces in Solids

1983 ◽  
Vol 25 ◽  
Author(s):  
J. S. Liu ◽  
R. W. Balluffi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Infinite Number ◽  
Elastic Energy ◽  
Driving Force ◽  
Boundary Type ◽  
Wide Range ◽  
Interphase Boundaries ◽  
Crystal Interfaces

ABSTRACTAttention is focused on the interactions which occur when lattice dislocations impinge on interfaces (i.e., grain boundaries, crystal/crystal interphase boundaries and crystal/amorphous boundaries) in solids. The lattice dislocations can generally dissociate into interface dislocations possessing smaller Burgers vectors under a driving force produced by a decrease in the elastic energy. For crystal/crystal interfaces, a wide range of possibilities exists, depending upon the grain boundary type, which extends from dissociation into a discrete number of interface dislocations to dissociations into a distribution consisting of, in the limit, an infinite number of interface dislocations possessing infinitesimal Bur.ers vectors. For crystal/ anorphous interfaces, the latter model is applicable. Examples of dissociations in these various interfaces are presented. The dissociation geometries and kinetics are described briefly. Some of the wider implications of these phenomena are mentioned.

Magnetically Driven Selective Grain Growth in Locally Deformed Zn Single Crystals

2004 ◽  
Vol 467-470 ◽  
pp. 763-770 ◽  
Author(s):  
P.J. Konijnenberg ◽  
Dmitri A. Molodov ◽  
Günter Gottstein
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Grain Growth ◽  
Driving Force ◽  
Grain Orientation ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Single Temperature ◽  
Individual Grains

In magnetically anisotropic materials a driving force for grain boundary migration can be induced by an external magnetic ¯eld. It is experimentally shown that annealing of locally deformed Zn single crystals in a suitably directed high magnetic ¯eld results in a growth of new individual grains. Velocities of some solitary moving grain boundaries were measured and their absolute mobilities were estimated at a single temperature. Results are discussed in terms of preferential grain orientation and boundary character.

The Surface Morphology of Titanium Nitride / Copper Bilayers Annealed at High Temperatures

1993 ◽  
Vol 318 ◽  
Author(s):  
Antonio C. Berti ◽  
Shyam P. Murarka ◽  
Laura E. Brooke
Keyword(s):  
Grain Boundary ◽  
Surface Morphology ◽  
Titanium Nitride ◽  
Grain Boundaries ◽  
Driving Force ◽  
Annealing Temperature ◽  
Boundary Energy ◽  
Strong Dependence ◽  
Copper Film ◽  
Copper Films

ABSTRACTBilayers of 40 nm titanium nitride and 500 nm copper were sputter deposited on oxidized silicon substrates. The films were annealed for one hour at temperatures from 400° C to 800° C in either vacuum or Ar/H2, ambients. Neither x-ray diffraction or Rutherford backscattering spectrometry indicated any interaction between the titanium nitride and copper films. While no differences in surface morphology were detected at annealing temperatures of less than 500° C, above this temperature a strong dependence on annealing ambient was found. In the vacuum annealed samples, surface grooves formed at the grain boundaries of the copper film. These grooves became progressively larger as the annealing temperature was increased, eventually leading to void formation. Only small grain boundary grooves were present in the Ar/H2, annealed films regardless of annealing temperature. The driving force for the formation of the grooves is believed to be a difference between the grain boundary and surface energies in the copper films. It is speculated that in Ar/H2 anneals this driving force is reduced because hydrogen segregates to the copper grain boundaries and lowers the grain boundary energy.The formation of grooves was found to retard copper grain growth and texturing. Resistivity of the copper film was also found to increase if the void density was sufficiently high.

scholarly journals Electrochemical drag effect on grain boundary motion in ionic ceramics

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
K. S. N. Vikrant ◽  
Wolfgang Rheinheimer ◽  
R. Edwin García
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Driving Forces ◽  
Ionic Species ◽  
Boundary Motion ◽  
Wide Range ◽  
Structural Interface ◽  
Applied Fields ◽  
Grain Boundary Motion ◽  
Boundary Core

Abstract The effects of drag imposed by extrinsic ionic species and point defects on the grain boundary motion of ionic polycrystalline ceramics were quantified for the generality of electrical, chemical, or structural driving forces. In the absence of, or for small driving forces, the extended electrochemical grain boundary remains pinned and symmetrically distributed about the structural interface. As the grain boundary begins to move, charged defects accumulate unsymmetrically about the structural grain boundary core. Above the critical driving force for motion, grain boundaries progressively shed individual ionic species, from heavier to lighter, until they display no interfacial electrostatic charge and zero Schottky potential. Ionic p–n junction moving grain boundaries that induce a finite electrostatic potential difference across entire grains are identified for high velocity grains. The developed theory is demonstrated for Fe-doped SrTiO3. The increase in average Fe concentration and grain boundary crystallographic misorientation enhances grain boundary core segregation and results in thick space charge layers, which leads to a stronger drag force that reduces the velocity of the interface. The developed theory sets the stage to assess the effects of externally applied fields such as temperature, electromagnetic fields, and chemical stimuli to control the grain growth for developing textured, oriented microstructures desirable for a wide range of applications.

The Interaction of Twin Boundaries with Grain Boundaries in YBa2Cu3O7-δ

1994 ◽  
Vol 357 ◽  
Author(s):  
Jenn-Yue Wang ◽  
Alexander H. King
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Small Angle ◽  
Driving Force ◽  
The Other ◽  
Twin Boundaries ◽  
Domain Structures ◽  
Tilt Boundaries ◽  
Symmetrical Tilt ◽  
System Energy

AbstractTwins in YBa2Cu3O7-δ may be “correlated” at [001] tilt grain boundaries (i.e. twin boundaries from one grain may meet twin boundaries from the other grain in quadruple junctions) and the twins may also be narrowed or “constricted” at the boundary. These effects are more pronounced in the regime of small angle grain boundaries. Based on TEM observations, a tentative threshold misorientation angle of approximately 15° is identified, below which there is a significant driving force reducing the system energy by correlation. The energies of various grain boundary domain structures associated with the twins were estimated on the basis of the dislocations they contain. Success has been obtained in explaining twin correlation in symmetrical tilt boundaries.

Magnetically Controlled Grain Boundary Motion and Grain Growth in Zinc

2013 ◽  
Vol 753 ◽  
pp. 107-112 ◽  
Author(s):  
Christoph Günster ◽  
Dmitri A. Molodov ◽  
Günter Gottstein
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Driving Force ◽  
Boundary Migration ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Cold Rolled ◽  
Grain Growth Kinetics ◽  
Grain Boundary Motion

The motion of grain boundaries in zinc bicrystals (99.995%) driven by the “magnetic” driving force was investigated. Planar symmetrical and asymmetrical tilt grain boundaries with rotation angles in the range between 60° and 90° were examined. At a given temperature the boundary migration rate was found to increase linearly with an applied driving force. The absolute grain boundary mobility was determined. The boundary mobility and its temperature dependence were found to depend on the misorientation angle and the inclination of the boundary plane. An application of a magnetic field during the annealing of cold rolled (90%) Zn-1.1%Al sheet specimens resulted in an asymmetry of the two major texture components. This is interpreted in terms of magnetically affected grain growth kinetics.

Microstructures, Grain Boundaries and Superplasticity in Fine Grained Ceramics

1990 ◽  
Vol 196 ◽  
Author(s):  
C. Carry
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Boundary Structure ◽  
Fine Grained ◽  
Chemical Effects ◽  
Liquid Phases ◽  
Grain Boundary Structure ◽  
Wide Range ◽  
Points Of View

ABSTRACTDeformation studies in compression and in tension have clearly shown evidence for superplasticity for a wide range of fine grained ceramics from both macroscopic and microscopic points of view. The main purpose of this paper is to focus attention on chemical effects in ceramic grain boundaries which can lead to a great variety of behavior. Grain boundary segregation or precipitation, residual impurities or doping elements, and glassy or liquid phases at grain boundaries can strongly affect the macroscopic flow properties of superplastic fine grained ceramics. Some microstructural and grain boundary features, mainly in two oxide materials (alumina and yttria doped zirconia), are analyzed, compared, and discussed in connection with their observed superplastic behavior. Special attention is devoted to the relation between the overall chemistry of the materials (impurities and doping elements) and to the grain boundary structure and chemistry (segregation, precipitation, intergranular phases). Some consequences and implications on the tailoring of ceramic microstructures for superplasticity are discussed. In addition, some recent hot forming and hot bonding experiments are also reported.

Evolution of the structure and grain boundary ensemble of nickel during diffusion annealing under conditions of a segregating impurity (silver) along grain boundaries

2021 ◽  
pp. 30-35
Author(s):  
E.V. Naydenkin ◽  
◽  
I.P. Mishin ◽  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Osmotic Pressure ◽  
Driving Force ◽  
Boundary Migration ◽  
Diffusion Annealing ◽  
Grain Boundary Migration

Investigations of the effect of an impurity (silver) segregating along the grain boundaries of nickel on the evolution of the structure and grain-boundary ensemble under conditions of diffusion annealing at a temperature of 823 K for 6 hours have been carried out. It is shown that, under these conditions, the development of a diffusion-induced recrystallization (DIR) process is observed in the Ni(Ag) system, in contrast to the Ni(Cu) system, in which the process of diffusion-induced grain boundary migration (DIGM) was observed. The estimates made have shown that a possible reason for the fact that diffusion-induced migration of grain boundaries practically does not occur in the Ni(Ag) system can be significantly lower than in the Ni(Cu) system the value of osmotic pressure as the driving force for the DIGM process.

Indentation strain burst phenomenon induced by grain boundaries in niobium

2004 ◽  
Vol 19 (8) ◽  
pp. 2478-2486 ◽  
Author(s):  
M.G. Wang ◽  
A.H.W. Ngan
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Experimental Results ◽  
Depth Sensing ◽  
Boundary Segment ◽  
Strain Burst ◽  
Boundary Type ◽  
Displacement Jump ◽  
Close Relationship ◽  
Indentation Strain

Using depth-sensing indentation, a pop-in phenomenon induced by grain boundaries, namely, a sudden indenter displacement jump when indented near a grain boundary segment, was observed in polycrystalline niobium. This grain-boundary type of pop-in occurs at a larger force than the initial elasto-plastic pop-in, which is observed with and without a grain boundary nearby. The experimental results show that this pop-in effect has a close relationship with the misorientation across the grain boundary. The occurrence of this pop-in phenomenon is rationalized in terms of slip transmission across the grain boundary.

Microstructure and properties of Cu-rich 123. Part I: Copper at the grain boundaries

1992 ◽  
Vol 7 (3) ◽  
pp. 572-579 ◽  
Author(s):  
J.P. Zhang ◽  
D.J. Li ◽  
L.D. Marks ◽  
C.H. Lin ◽  
J.A. Eades ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Initial Material ◽  
Planar Defects ◽  
Boundary Density ◽  
Excess Copper ◽  
Wide Range ◽  
Full Picture ◽  
Conventional Material ◽  
Grain Boundary Pinning

A range of copper-rich bulk YBa2Cu3+xO7+y superconductors have been prepared by mixing excess copper oxide in the initial material and characterized for their magnetic properties and microstructure. The microstructure of the materials exhibits a high density of planar defects at the grain boundaries and a grain boundary amorphous phase. There is a small increase in the magnetic Jc at 4.5 K but a decrease compared to a conventional material at 77 K, and there is no correlation of the magnetic Jc with the twin boundary density. The change in Jc can be understood if the grain boundary pinning is strong at 4.5 K but weak at 77 K. Data obtained using a very wide range of different microstructure characterization techniques clearly indicate the dangers of relying on only one technique to obtain a full picture of the material.

Chromium Distribution in CoCrTa/Cr Longitudinal Recording Media

1998 ◽  
Vol 517 ◽  
Author(s):  
J.E. Wittig ◽  
T.P. Nolan ◽  
R. Sinclair ◽  
J. Bentley
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Recording Media ◽  
Resolution Electron ◽  
Wide Range ◽  
Composition Profiles ◽  
Longitudinal Recording ◽  
Cr Concentration ◽  
Random Angle

AbstractThe current study of CoCr12Ta4/Cr longitudinal recording media combines high resolution electron microscopy (HRTEM) with nanoprobe energy dispersive spectroscopy (EDS) and energy-filtered imaging (EFTEM) to correlate the Cr distribution with specific microstructural features. EFTEM images show Cr enrichment at grain boundaries, both random angle boundaries and 90° bicrystal boundaries. Cr segregation within grains is also observed in the elemental maps. This intragrain segregation often occurs at a series of defects that may define separately nucleated grains having 00 misorientation. Nanoprobe EDS measurements indicate that these defects contain localized concentrations of 25 to 30 % Cr. The random angle grain boundary Cr concentration occurs with a wide range, 19 to 36 at% (mean 22%) whereas the more crystallographically related 900 boundaries contain less Cr with less variation, 15 to 21 at% (mean 17% Cr). Composition profiles across grain boundaries using both nanoprobe EDS and EFTEM images show the full-width-half-maximum of the segregation to be approximately 4 nm, with Cr depleted regions next to the grain boundary having less than 7 at% Cr. The Ta concentration revealed no statistical evidence of segregation.

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