Resolving the geometrically necessary dislocation content in severely deformed aluminum by transmission Kikuchi diffraction

2018 ◽  
Vol 140 ◽  
pp. 225-232 ◽  
Author(s):  
Soroosh Naghdy ◽  
Patricia Verleysen ◽  
Roumen Petrov ◽  
Leo Kestens
Keyword(s):  
Geometrically Necessary Dislocation ◽  
Dislocation Content

Strain-Induced Selective Growth in 1.5% Temper-Rolled Fe∼1%Si

2011 ◽  
Vol 17 (3) ◽  
pp. 362-367 ◽  
Author(s):  
Tricia A. Bennett ◽  
Peter N. Kalu ◽  
Anthony D. Rollett
Keyword(s):  
Electron Backscatter Diffraction ◽  
Selective Growth ◽  
Stored Energy ◽  
Grain Sizes ◽  
Geometrically Necessary Dislocation ◽  
Electron Backscatter ◽  
Ebsd Technique ◽  
Backscatter Diffraction ◽  
Dislocation Content

AbstractStrain-induced selective growth was investigated in a 1.5% temper-rolled Fe∼1%Si alloy using the electron backscatter diffraction (EBSD) technique. The EBSD technique was used to quantify the presence of orientation spreads within grains and to show that this particular case of selective growth can be directly related to differences in stored energy as reflected in the geometrically necessary dislocation content. The differences in stored energy were sufficient to give rise to selective growth as evidenced by bi-modal grain sizes.

Length-Scale-Dependent Micromechanical Modeling for Precipitate Hardening in Inconel 718 Superalloy

2021 ◽  
Vol 315 ◽  
pp. 84-89
Author(s):  
Chang Feng Wan ◽  
Dong Feng Li ◽  
Hai Long Qin ◽  
Ji Zhang ◽  
Zhong Nan Bi
Keyword(s):  
Dislocation Density ◽  
Strain Gradient ◽  
Inconel 718 ◽  
Micromechanical Modeling ◽  
Fe Model ◽  
Gradient Effect ◽  
Fine Mesh ◽  
Geometrically Necessary Dislocation ◽  
In718 Superalloy ◽  
Inconel 718 Superalloy

In this paper, a micromechanical finite element (FE) model has been proposed to investigate the effect of the nanoscale precipitates on the development of microplasticity for Inconel 718 (IN718) superalloy. A strain gradient crystal plasticity formulation has been developed with the considerations of the evolution of statistically stored dislocation density and geometrically necessary dislocation density. The mesh convergence has been examined, showing that sufficiently fine mesh is required in the FE model. The results show that the model with strain gradient effect incorporated shows less peak plastic strain and higher value of dislocation density than the model with no strain gradient effect. The present study indicates that the strain hardening process at the scale of strengthening precipitate is mainly governed by the evolution of geometrically necessary dislocation densities.

scholarly journals Disclinations and disconnections in minerals and metals

2019 ◽  
Vol 117 (1) ◽  
pp. 196-204 ◽  
Author(s):  
John P. Hirth ◽  
Greg Hirth ◽  
Jian Wang
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Boundary Sliding ◽  
Dislocation Content

A different type of defect, the coherency disclination, is added to disclination types. Disconnections that include disclination content are considered. A criterion is suggested to distinguish disconnections with dislocation content from those with disclination content. Electron microscopy reveals unit disconnections in a low albite grain boundary, defects important in grain boundary sliding. Disconnections of varying step heights are displayed and shown to define both deformed and recovered structures.

Experimental lower bounds on geometrically necessary dislocation density

2010 ◽  
Vol 26 (8) ◽  
pp. 1097-1123 ◽  
Author(s):  
J.W. Kysar ◽  
Y. Saito ◽  
M.S. Oztop ◽  
D. Lee ◽  
W.T. Huh
Keyword(s):  
Dislocation Density ◽  
Lower Bounds ◽  
Geometrically Necessary Dislocation

Estimation of geometrically necessary dislocation density from filtered EBSD data by a local linear adaptation of smoothing splines

2019 ◽  
Vol 52 (3) ◽  
pp. 548-563 ◽  
Author(s):  
Anthony Seret ◽  
Charbel Moussa ◽  
Marc Bernacki ◽  
Javier Signorelli ◽  
Nathalie Bozzolo
Keyword(s):  
Electron Backscatter Diffraction ◽  
Smoothing Splines ◽  
Data Sets ◽  
Square Grid ◽  
Orientation Gradient ◽  
Geometrically Necessary Dislocation ◽  
Ebsd Data ◽  
Local Linear ◽  
Density Values ◽  
Hexagonal Grids

An implementation of smoothing splines is proposed to reduce orientation noise in electron backscatter diffraction (EBSD) data, and subsequently estimate more accurate geometrically necessary dislocation (GND) densities. The local linear adaptation of smoothing splines (LLASS) filter has two advantages over classical implementations of smoothing splines: (1) it allows for an intuitive calibration of the fitting versus smoothing trade-off and (2) it can be applied directly and in the same manner to both square and hexagonal grids, and to 2D as well as to 3D EBSD data sets. Furthermore, the LLASS filter calculates the filtered orientation gradient, which is actually at the core of the method and which is subsequently used to calculate the GND density. The LLASS filter is applied on a simulated low-misorientation-angle boundary corrupted by artificial orientation noise (on a square grid), and on experimental EBSD data of a compressed Ni-base superalloy (acquired on a square grid) and of a dual austenitic/martensitic steel (acquired on an hexagonal grid). The LLASS filter leads to lower GND density values as compared to raw EBSD data sets, as a result of orientation noise being reduced, while preserving true GND structures. In addition, the results are compared with those of filters available in theMTEXtoolbox.

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