Electron Channeling Contrast Imaging of Plastic Deformation Induced by Indentation in Polycrystalline Nickel

2013 ◽  
Vol 19 (6) ◽  
pp. 1620-1631 ◽  
Author(s):  
Shirin Kaboli ◽  
Dina Goldbaum ◽  
Richard R. Chromik ◽  
Raynald Gauvin
Keyword(s):  
Plastic Deformation ◽  
Strain Field ◽  
Surface Preparation ◽  
Preparation Technique ◽  
Ion Milling ◽  
Contrast Imaging ◽  
Polycrystalline Nickel ◽  
Electron Backscattered Diffraction ◽  
Bulk Specimen ◽  
Electron Channeling

AbstractVickers microindentation and Berkovich nanoindentation tests were carried out on a polycrystalline nickel (Ni) bulk specimen. Electron channeling contrast imaging (ECCI) in conjunction with electron backscattered diffraction was used to image and characterize plastic deformation inside and around the indents using a field emission scanning electron microscope. The ECCI was performed with a 5 keV beam energy and 0° tilt specimen position. The strain field distribution, slip lines, and Taylor lattices were imaged on an indented surface. Orientation mapping was used to investigate the local crystallographic misorientation and identify specific ⟨110⟩ slip systems. An ion milling surface preparation technique was used to remove materials from the surface which permitted the study of deformed microstructure below the indent. A dislocation density of 1011 cm−2 was calculated based on the curvature of bend contours observed in the ECCI micrographs obtained from the Vickers indents. A yield strength of 500 MPa was calculated based on the size of the strain field measured from the ECCI micrographs of the nanoindents. The combination of ion milling, ECCI, and electron backscattered diffraction was shown to be beneficial to investigate the indentation-induced plastic deformation in a polycrystalline Ni bulk specimen.

scholarly journals The Use of Ion Milling for Surface Preparation for EBSD Analysis

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3970
Author(s):  
Wojciech J. Nowak
Keyword(s):  
Plasma Etching ◽  
Ion Beam ◽  
Metallic Matrix ◽  
Surface Preparation ◽  
Optical Emission ◽  
Alternative Methods ◽  
Ebsd Analysis ◽  
Crystallographic Structure ◽  
Ion Milling ◽  
Electron Backscattered Diffraction

An electron backscattered diffraction (EBSD) method provides information about the crystallographic structure of materials. However, a surface subjected to analysis needs to be well-prepared. This usually requires following a time-consuming procedure of mechanical polishing. The alternative methods of surface preparation for EBSD are performed via electropolishing or focus ion beam (FIB). In the present study, plasma etching using a glow discharge optical emission spectrometer (GD-OES) was applied for surface preparation for EBSD analysis. The obtained results revealed that plasma etching through GD-OES can be successfully used for surface preparation for EBSD analysis. However, it was also found that the plasma etching is sensitive for the alloy microstructure, i.e., the presence of intermetallic phases and precipitates such as carbides possess a different sputtering rate, resulting in non-uniform plasma etching. Preparation of the cross-section of oxidized CM247 revealed a similar problem with non-uniformity of plasma etching. The carbides and oxide scale possess a lower sputtering rate than the metallic matrix, which caused formation of relief. Based on obtained results, possible resolutions to suppress the effect of different sputtering rates are proposed.

scholarly journals A Dislocation-scale Characterization of the Evolution of Deformation Microstructures around Nanoindentation Imprints in a TiAl Alloy

2018 ◽  
Author(s):  
Antoine Guitton ◽  
Hana Kriaa ◽  
Emmanuel Bouzy ◽  
Julien Guyon ◽  
Nabila Maloufi
Keyword(s):  
Plastic Deformation ◽  
Room Temperature ◽  
Tial Alloy ◽  
Mechanical Twinning ◽  
Contrast Imaging ◽  
Electron Channeling ◽  
The Poor ◽  
Before And After ◽  
Scale Characterization

In this work, plastic deformation was locally introduced at room temperature by nanoindentation on a γ-TiAl based alloy. Comprehensive analyzes of microstructures were performed before and after deformation. In particular, the Burgers vectors, the line directions and the mechanical twinning systems were studied via accurate electron channeling contrast imaging. Accommodation of the deformation are reported and a scenario is proposed. All features help to explain the poor ductility of the TiAl based alloys at room temperature.

scholarly journals A Dislocation-Scale Characterization of the Evolution of Deformation Microstructures around Nanoindentation Imprints in a TiAl alloy

2018 ◽  
Author(s):  
Antoine Guitton ◽  
Hana Kriaa ◽  
Emmanuel Bouzy ◽  
Julien Guyon ◽  
Nabila Maloufi
Keyword(s):  
Plastic Deformation ◽  
Room Temperature ◽  
Tial Alloy ◽  
Mechanical Twinning ◽  
Contrast Imaging ◽  
Electron Channeling ◽  
The Poor ◽  
Before And After ◽  
Scale Characterization

In this work, plastic deformation was locally introduced at room temperature by nanoindentation on a γ-TiAl based alloy. Comprehensive analyzes of microstructures were performed before and after deformation. In particular, the Burgers vectors, the line directions and the mechanical twinning systems were studied via accurate electron channeling contrast imaging. Accommodation of the deformation are reported and a scenario is proposed. All features help to explain the poor ductility of the TiAl based alloys at room temperature.

scholarly journals In Situ Macroscopic Tensile Testing in SEM and Electron Channeling Contrast Imaging: Pencil Glide Evidenced in a Bulk β-Ti21S Polycrystal

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2479
Author(s):  
Meriem Ben Haj Slama ◽  
Nabila Maloufi ◽  
Julien Guyon ◽  
Slim Bahi ◽  
Laurent Weiss ◽  
...  
Keyword(s):  
Tensile Testing ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Contrast Imaging ◽  
Bulk Specimen ◽  
Electron Channeling ◽  
Uniaxial Tensile Testing ◽  
Stress States ◽  
Tangled Dislocation

In this paper, we report the successful combination of macroscopic uniaxial tensile testing of bulk specimen combined with In situ dislocation-scale observations of the evolution of deformation microstructures during loading at several stress states. The dislocation-scale observations were performed by Accurate Electron Channeling Contrast Imaging in order to follow the defects evolution and their interactions with grain boundaries for several regions of interest during macroscopic loading. With this novel in situ procedure, the slip systems governing the deformation in polycrystalline bulk β-Ti21S are tracked during the macroscopic uniaxial tensile test. For instance, curved slip lines that are associated with “pencil glide” phenomenon and tangled dislocation networks are evidenced.

scholarly journals Microstructural Characterization of Mg-Al-Ca Alloys Using Ion Milling Surface Preparation Technique

2013 ◽  
Vol 19 (S2) ◽  
pp. 1756-1757
Author(s):  
S. Kaboli ◽  
H. Demers ◽  
N. Brodusch ◽  
R. Gauvin
Keyword(s):  
Surface Preparation ◽  
Microstructural Characterization ◽  
Preparation Technique ◽  
Ion Milling

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

scholarly journals Comparison of dislocation characterization by electron channeling contrast imaging and cross-correlation electron backscattered diffraction

2018 ◽  
Vol 184 ◽  
pp. 125-133 ◽  
Author(s):  
Bret E. Dunlap ◽  
Timothy J. Ruggles ◽  
David T. Fullwood ◽  
Brian Jackson ◽  
Martin A. Crimp
Keyword(s):  
Cross Correlation ◽  
Contrast Imaging ◽  
Electron Backscattered Diffraction ◽  
Electron Channeling

Experimental Evaluation of the Cyclic Slip Irreversibility Factor

2011 ◽  
Vol 465 ◽  
pp. 223-226 ◽  
Author(s):  
Anja Weidner ◽  
Maxime Sauzay ◽  
Werner Skrotzki
Keyword(s):  
Half Cycle ◽  
Contrast Imaging ◽  
Polycrystalline Nickel ◽  
Electron Backscattered Diffraction ◽  
Ductile Metals ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electron Channelling ◽  
Persistent Slip Bands ◽  
Cyclic Slip

Cyclic slip irreversibility is one of the most important features of fatigue processes in ductile metals because it induces surface relief evolutions during cycling which are mainly responsible for crack initiation. The reversible and irreversible parts of the slip within persistent slip bands (PSBs) in polycrystalline nickel are measured directly after half-cycle deformation and one full cycle on specimen surfaces once more well-polished after 60% of fatigue life using atomic force microscopy (AFM) and different techniques of scanning electron microscopy as electron channelling contrast imaging and electron backscattered diffraction. Using AFM measures on the same slip steps after half-cycle and full cycle, the cyclic slip irreversibility factor is directly evaluated and discussed with respect to the literature.

Strain analysis with nanometer resolution using a conventional transmission electron microsopy technique: electron diffraction contrast imaging revisited

1995 ◽  
Vol 53 ◽  
pp. 168-169
Author(s):  
Koenraad G F Janssens ◽  
Omer Van der Biest ◽  
Jan Vanhellemont ◽  
Herman E Maes ◽  
Robert Hull
Keyword(s):  
Electron Diffraction ◽  
Strain Field ◽  
Elastic Strain ◽  
Strain Analysis ◽  
Local Strain ◽  
Contrast Imaging ◽  
Strain Characterization ◽  
Physical Mechanisms ◽  
Diffraction Contrast ◽  
Transmission Electron

There is a growing need for elastic strain characterization techniques with submicrometer resolution in several engineering technologies. In advanced material science and engineering the quantitative knowledge of elastic strain, e.g. at small particles or fibers in reinforced composite materials, can lead to a better understanding of the underlying physical mechanisms and thus to an optimization of material production processes. In advanced semiconductor processing and technology, the current size of micro-electronic devices requires an increasing effort in the analysis and characterization of localized strain. More than 30 years have passed since electron diffraction contrast imaging (EDCI) was used for the first time to analyse the local strain field in and around small coherent precipitates1. In later stages the same technique was used to identify straight dislocations by simulating the EDCI contrast resulting from the strain field of a dislocation and comparing it with experimental observations. Since then the technique was developed further by a small number of researchers, most of whom programmed their own dedicated algorithms to solve the problem of EDCI image simulation for the particular problem they were studying at the time.

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