Stress Localization Resulting from Grain Boundary Dislocation Interactions in Relaxed and Defective Grain Boundaries

2019 ◽  
Vol 51 (2) ◽  
pp. 667-683 ◽  
Author(s):  
Bryan Kuhr ◽  
Diana Farkas ◽  
Ian M. Robertson ◽  
Drew Johnson ◽  
Gary Was
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Dislocation ◽  
Dislocation Interactions ◽  
Stress Localization

Observations of dislocation interactions with recrystallized grain boundaries

1988 ◽  
Vol 46 ◽  
pp. 628-629
Author(s):  
C. W. Price
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Dislocation Structure ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
High Dislocation Density ◽  
High Angle ◽  
Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

scholarly journals Atomistic survey of grain boundary-dislocation interactions in FCC nickel

2019 ◽  
Vol 164 ◽  
pp. 171-185 ◽  
Author(s):  
Devin W. Adams ◽  
David T. Fullwood ◽  
Robert H. Wagoner ◽  
Eric R. Homer
Keyword(s):  
Grain Boundary ◽  
Boundary Dislocation ◽  
Dislocation Interactions

Grain Boundary Responses to Local and Applied Stress: An In Situ TEM Deformation Study

2006 ◽  
Vol 976 ◽  
Author(s):  
Bryan Miller ◽  
Jamey Fenske ◽  
Dong Su ◽  
Chung-Ming Li ◽  
Lisa Dougherty ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Transmission Electron Microscope ◽  
In Situ Tem ◽  
Deformation Twins ◽  
Transmission Electron ◽  
Dislocation Interactions

AbstractDeformation experiments at temperatures between 300 and 750 K have been performed in situ in the transmission electron microscope to investigate dislocation interactions and reactions with grain boundaries and other obstacles. Dislocations, both partial and perfect, as well as deformation twins have been observed being emitted from grain boundaries and, in some cases, even the same grain boundary. The ejection of dislocations from the grain boundary can result in its partial or total annihilation. In the latter case, the disintegration of the grain boundary was accompanied by grain growth and a change in misorientation.

The Slip Transfer Process Through Grain Boundaries in HCP Ti

1993 ◽  
Vol 319 ◽  
Author(s):  
J. Shirokoff ◽  
I.M. Robertson ◽  
H.K. Birnbaum
Keyword(s):  
Grain Boundary ◽  
Slip System ◽  
Grain Boundaries ◽  
Slip Systems ◽  
Boundary Dislocation ◽  
Burgers Vector ◽  
Slip Transfer ◽  
Transmission Electron ◽  
Fcc Materials

AbstractInformation on the mechanisms of slip transfer across grain boundaries in an HCP α-Ti alloy has been obtained from deformation experiments performed In situ in the transmission electron microscope. Initially, lattice dislocations are accommodated within the grain boundary until a critical local dislocation density is reached. The boundary then responds by activating slip in the adjoining grain on the slip system experiencing the highest local resolved shear stress and producing the residual grain-boundary dislocation with the smallest Burgers vector. Slip on secondary slip systems may be initiated provided they reduce the magnitude of the Burgers vector of, or eliminate, the residual grainboundary dislocation. The selection rules used to predict the slip system activated by the grain boundary are the same as apply in ordered and disordered FCC materials.

scholarly journals Burgers Vectors in Secondary Grain Boundary Dislocation Structures for near S9, S27 and S81 Boundaries

1985 ◽  
Vol 38 (3) ◽  
pp. 449 ◽  
Author(s):  
CT Forwood ◽  
LM Clarebrough
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Electron Micrographs ◽  
Image Matching ◽  
Boundary Dislocation

The Burgers vectors of secondary grain boundary dislocations, forming networks in near ~9, ~27a, ~27b and ~81a grain boundaries in polycrystalline specimens of a Cu +6 at. % Si alloy, have been determined using the technique of image matching, which involves a comparison of experimental and theoretical electron micrographs. In all cases, the Burgers vectors of the secondary grain boundary dislocations were found to be vectors of the DSC lattice corresponding to the appropriate CSL orientation. Further, in most cases, the Burgers vectors were found to be basis DSC vectors.

Effect of Grain Boundary Ledges on the Flow Stress in Nickel

1977 ◽  
Vol 35 ◽  
pp. 284-285
Author(s):  
Eswarahalli S. Venkatesh ◽  
L.E. Murr
Keyword(s):  
Flow Stress ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Materials ◽  
Structure And Properties ◽  
Boundary Dislocation ◽  
Dislocation Source ◽  
Type Relation ◽  
Ledge Density ◽  
Boundary Ledge

In a recent paper1 it was shown that grain boundary ledge structure can be changed by appropriate thermomechanical treatments. Grain boundary ledges are sources of dislocations2. Recently the effects of grain boundaries on the mechanical properties in metals and alloys were studied3,4. For a few years now the structure and properties of grain boundaries and their control have been considered as a means of strengthening polycrystalline materials5,6. Li5 has derived a Hall-Petch type relation in terms of grain boundary dislocation source (ledge) density, m, in the form where L is the grain size, σ0 and α are constants, and G ana b have the usual meaning. The influence of grain boundary ledge density, on the flow stress is considered in this paper.In the present work, pure (99.98%) nickel sheet mill rolled (hot) to 0.022 in. thick was used.

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