Elemental Segregation at Grain Boundaries in Three-Phase Ceramics Depends on Sintering Technique

2020 ◽  
Author(s):  
Komal Syed ◽  
Mingjie Xu ◽  
Kenta K. Ohtaki ◽  
David Kok ◽  
Keyur K. Karandikar ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Elemental Segregation ◽  
Three Phase

Atom probe tomographic study of elemental segregation at grain boundaries for a peak-aged Al–Zn–Mg alloy

2014 ◽  
Vol 79 ◽  
pp. 1-4 ◽  
Author(s):  
X.Y. Sun ◽  
B. Zhang ◽  
H.Q. Lin ◽  
Y. Zhou ◽  
L. Sun ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Atom Probe ◽  
Mg Alloy ◽  
Elemental Segregation ◽  
Peak Aged

Impact of Energy-Dispersive Spectrometry in Materials Science Microanalysis

1998 ◽  
Vol 4 (6) ◽  
pp. 567-575 ◽  
Author(s):  
David B. Williams
Keyword(s):  
Grain Boundaries ◽  
Energy Dispersive Spectrometry ◽  
Equilibrium Phase ◽  
Boundary Segregation ◽  
Temper Embrittlement ◽  
Energy Dispersive ◽  
Small Scale ◽  
X Ray ◽  
Elemental Segregation

X-ray microanalysis of materials using energy-dispersive spectrometry (EDS) has made the greatest impact in studies of compositional changes at atomic-level interfaces. The small physical dimensions of the silicon detector make EDS the X-ray analyzer of choice for analytical transmission electron microscopy (AEM). X-ray analysis of thin foils in the AEM has contributed to our understanding of elemental segregation to interphase interfaces and grain boundaries, as well as other planar defects. Measurement of atomic diffusion on a small scale close to interphase interfaces has permitted determination of substitutional atomic diffusivities several orders of magnitude smaller than previously possible and has also led to the determination of low-temperature equilibrium phase diagrams through the measurement of local interface compositions. Elemental segregation to grain boundaries is responsible for such deleterious behavior as temper embrittlement, stress-corrosion cracking, and other forms of intergranular failure. On the other hand, segregation can bring about improvement in behavior: sintering aids in ceramics and de-embrittlement of intermetallics. EDS in the AEM has been responsible for quantitative analysis of all aspects of the segregation process and, more recently, in combination with electron energy-loss spectrometry (EELS) has given insight into why boundary segregation results in such significant macroscopic changes in properties.

scholarly journals Nanoscale Electrochemistry in a Copper/Aqueous/Oil Three-phase System: Surface Structure-Activity-Corrosion Potential Relationships 

2021 ◽  
Author(s):  
Enrico Daviddi ◽  
Viacheslav Shkirskiy ◽  
Paul Kirkman ◽  
Mathew P Robin ◽  
Cameron Luke Bentley ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Surface Structure ◽  
Corrosion Potential ◽  
Electrochemical Cell ◽  
Phase System ◽  
Metal Electrodes ◽  
Structure Activity ◽  
Three Phase ◽  
Cell Microscopy ◽  
Crystallographic Orientations

Practically important metal electrodes are usually polycrystalline, comprising surface grains of many different crystallographic orientations, as well as grain boundaries. In this study, scanning electrochemical cell microscopy (SECCM) is applied...

scholarly journals Analysis of Elemental Segregation in a Microalloyed Cast Steel

2013 ◽  
Vol 652-654 ◽  
pp. 2465-2468 ◽  
Author(s):  
Jing Wei Zhao ◽  
Zheng Yi Jiang ◽  
Dong Bin Wei
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Cast Steel ◽  
Central Zone ◽  
Energy Dispersive ◽  
Surface Zone ◽  
Quantitative Investigation ◽  
X Ray ◽  
Elemental Segregation

Quantitative investigation is made on the elemental segregation in different zones of a heavy microalloyed cast steel by energy dispersive X-ray spectroscopy. It is demonstrated that C shows serious segregation tendency than that of Mn and Si, and the degree of C segregation in the surface zone is higher than that in the central zone. C enrichment is generally observed at both dendrite arm and grain boundaries, and more C segregation at dendrite arm boundary in contrast to that at grain boundary is found in this steel. The distribution of C concentration shows a decreased trend from root to tip along the dendrite arm boundary. The C concentration at trigeminal boundary intersection shows higher level than that at other position of the grain boundaries.

Carrier Transport Through Grain Boundaries in Hydrogenated Microcrystalline Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
S. Grebner ◽  
F. Wang ◽  
R. Schwarz
Keyword(s):  
Activation Energy ◽  
Grain Boundaries ◽  
Carrier Transport ◽  
Structural Information ◽  
Dark Conductivity ◽  
Microcrystalline Silicon ◽  
X Ray ◽  
Fermi Level Pinning ◽  
X Ray Scattering ◽  
Three Phase

ABSTRACTTo analyse the influence of the grain boundaries (gb) on the transport of carriers in hydrogenated microcrystalline silicon (μC-Si:H) the ambipolar diffusion length (LLMB) was measured by SSPG. In addition, the films were characterised by photo-conductivity, dark conductivity activation energy, Urbach energy (determined by CPM), hydrogen effusion, Raman spectroscopy, X-ray scattering and optical transmission.The sample series was prepared by PECVD of SiH4 diluted with increasing H2 content. Taking the structural information by Raman spectra and X-ray into account, we explain our optical and activation energy measurements within a three-phase-model (amorphous phase, crystalline phase, gb) and a Fermi level pinning in μc-Si:H.

Intentional and unintentional elemental segregation to grain boundaries in a Ni-rich nanocrystalline alloy

2018 ◽  
Vol 54 (4) ◽  
pp. 3496-3508 ◽  
Author(s):  
C. J. Marvel ◽  
B. C. Hornbuckle ◽  
K. A. Darling ◽  
M. P. Harmer
Keyword(s):  
Grain Boundaries ◽  
Nanocrystalline Alloy ◽  
Elemental Segregation

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 176-177
Author(s):  
D. E. Fornwalt ◽  
A. R. Geary ◽  
B. H. Kear
Keyword(s):  
Electron Microscope ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Volume ◽  
Precipitate Morphology ◽  
Stress Rupture Life ◽  
Nickel Base ◽  
Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

Measurement of the Displacement Across a Coincidence Grain Boundary

1977 ◽  
Vol 35 ◽  
pp. 124-125
Author(s):  
J. W. Matthews ◽  
W. M. Stobbs
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Stacking Fault ◽  
The Other ◽  
Measuring Technique ◽  
High Angle ◽  
Twin Boundaries ◽  
Rigid Displacement ◽  
Cubic Crystals ◽  
Lattice Displacement

Many high-angle grain boundaries in cubic crystals are thought to be either coincidence boundaries (1) or coincidence boundaries to which grain boundary dislocations have been added (1,2). Calculations of the arrangement of atoms inside coincidence boundaries suggest that the coincidence lattice will usually not be continuous across a coincidence boundary (3). There will usually be a rigid displacement of the lattice on one side of the boundary relative to that on the other. This displacement gives rise to a stacking fault in the coincidence lattice.Recently, Pond (4) and Smith (5) have measured the lattice displacement at coincidence boundaries in aluminum. We have developed (6) an alternative to the measuring technique used by them, and have used it to find two of the three components of the displacement at {112} lateral twin boundaries in gold. This paper describes our method and presents a brief account of the results we have obtained.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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