Characterization of Intergranular Phases in Doped Zirconia Polycrystals

1999 ◽  
Vol 589 ◽  
Author(s):  
N. D. Evans ◽  
P. H. Imamura ◽  
J. Bentley ◽  
M. L. Mecartney
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Analytical Electron Microscopy ◽  
Tetragonal Zirconia ◽  
Barium Ions ◽  
Analytical Electron ◽  
Scanning Transmission ◽  
Triple Points ◽  
Boundary Chemistry

AbstractAnalytical electron microscopy at high spatial resolution in a scanning-transmission mode has been used to investigate the effects of glassy or crystalline material additions on grain boundary chemistry in yttria-stabilized zirconia polycrystals. Powders of additive phase were mixed into 3-mol% yttria-stabilized tetragonal zirconia polycrystals (‘3Y-TZP’) or 8-mol% yttria-stabilized cubic zirconia polycrystals (‘8Y-CSZ’). Zirconias processed without additive phases were also examinedWithout additives, grain boundaries were depleted in zirconium and enriched in yttrium. In 3Y-TZP with I wt% borosilicate glass, silicon was observed only at triple points, but not in grain boundaries. In 3Y-TZP with 1 wt% barium silicate glass, barium was observed both along grain boundaries and at triple points, whereas silicon was detected only within the triple points. This suggests either the composition of the additive phase at the grain boundary is different from that at the triple points, or that barium ions segregate to grain boundaries during processing. In 8Y-CSZ with I wt% silica, silicon was observed in grain boundaries by an EDS spatial differencing technique. In 8Y-CSZ with 10 wt% alumina, EDS revealed aluminum at all grain boundaries examined

scholarly journals Microstructural Characterization of Multiphase Coatings Produced By Chemical Vapor Deposition

1989 ◽  
Vol 168 ◽  
Author(s):  
R. A. Lowden ◽  
K. L. More ◽  
T. M. Besmann ◽  
R. D. James
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Analytical Electron Microscopy ◽  
Chemical Vapor ◽  
Microstructural Characterization ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Analytical Electron ◽  
Scanning Transmission

AbstractChemical vapor deposition has been utilized to produce ternary, multiphase coatings of various compositions of silicon carbide (SiC) with Ti, Cr, and Mo. Thermodynamic calculations have been performed for a variety of experimental conditions in each system. Scanning, transmission and analytical electron microscopy, and X-ray diffraction techniques have been used to characterize the microstructures and to determine compositions.

Observation of grain boundary segregation in advanced ceramics using high-resolution imaging SIMS

1995 ◽  
Vol 53 ◽  
pp. 324-325
Author(s):  
R. Levi-Setti ◽  
K. K. Soni ◽  
J. M. Chabala ◽  
A. M. Thompson
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
High Spatial Resolution ◽  
Imaging Techniques ◽  
Boundary Segregation ◽  
Ion Microprobe ◽  
Broad Beam ◽  
Resolution Imaging ◽  
Boundary Chemistry

The significance of grain boundaries in controlling processing and properties of ceramics is widely acknowledged. Through the addition of suitable dopants to ceramics, their processability and properties can be improved. These dopants may segregate to grain boundaries, but the characterization of boundary chemistry is a challenging task. Studies of segregation phenomena require the application of high-lateralresolution techniques such as STEM/AEM or surface sensitive techniques such as AES, XPS. These techniques require rigorous sample preparation and have their limitations.The scanning ion microprobe is a powerful tool that has exhibited unprecedented potential in the characterization of grain boundaries in ceramics. When interfaced to a mass spectrometer (magnetic sector in our case), this instrument allows mapping of many trace elements at nanometer level in bulk specimens. The combination of excellent sensitivity and high spatial resolution enables direct imaging of grain boundary segregants. The results thus obtained are free from artifacts that typically complicate analysis with broad beam, non-imaging techniques.

High Spatial Resolution X-ray Microanalysis of Radiation-Induced Segregation in Proton-Irradiated Stainless Steels

1999 ◽  
Vol 589 ◽  
Author(s):  
E.A. Kenik ◽  
J.T. Busby ◽  
G.S. Was
Keyword(s):  
Grain Boundaries ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Scanning Transmission ◽  
Spatial Redistribution ◽  
Radiation Induced ◽  
Composition Profiles ◽  
Compositional Changes

AbstractThe spatial redistribution of alloying elements and impurities near grain boundaries in several stainless steel alloys arising from non-equilibrium processes have been measured by analytical electron microscopy (AEM) in a field emission scanning transmission electron microscope. Radiation-induced segregation (RIS) has been shown to result in significant compositional changes at point defects sinks, such as grain boundaries. The influence of irradiation dose and temperature, alloy composition, prior heat treatment, and post-irradiation annealing on the grain boundary composition profiles have been investigated. Understanding the importance of these microchemical changes relative to the radiation-induced microstructural change in irradiation-assisted stress corrosion cracking (IASCC) of the irradiated materials is the primary goal of this study.

Grain Boundary Chemistry in Al-Cu Metallizations as Determined by Analytical Electron Microscopy

1991 ◽  
Vol 229 ◽  
Author(s):  
J. R. Michael ◽  
A. D. Romig ◽  
D. R. Frear
Keyword(s):  
Electron Microscopy ◽  
Integrated Circuits ◽  
Grain Boundary ◽  
Analytical Electron Microscopy ◽  
Second Phase ◽  
Collector Plate ◽  
Analytical Electron ◽  
Cu Thin Film ◽  
Boundary Chemistry ◽  
Interconnect Lines

AbstractAl with additions of Cu is commonly used as the conductor metallizations for integrated circuits (ICs). As the packing density of ICs increases, interconnect lines are required to carry ever higher current densities. Consequently, reliability due to electromigration failure becomes an increasing concern. Cu has been found to increase the lifetimes of these conductors, but the mechanism by which electromigration is improved is not yet fully understood. In order to evaluate certain theories of electromigration it is necessary to have a detailed description of the Cu distribution in the Al microstructure, with emphasis on the distribution of Cu at the grain boundaries. In this study analytical electron microscopy (AEM) has been used to characterize grain boundary regions in an Al-2 wt.% Cu thin film metallization on Si after a variety of thermal treatments. The results of this study indicate that the Cu distribution is dependent on the thermal annealing conditions. At temperatures near the θ phase (CuAl2) solvus, the Cu distribution may be modelled by the collector plate mechanism, in which the grain boundary is depleted in Cu relative to the matrix. At lower temperatures, Cu enrichment of the boundaries occurs, perhaps as a precursor to second phase formation. Natural cooling from the single phase field produces only grain boundary depletion of Cu consistent with the collector-plate mechanism. The kinetic details of the elemental segregation behavior derived from this study can be used to describe microstructural evolution in actual interconnect alloys.

Grain Boundary Chemical Analysis Using Intense Electron Beams

1998 ◽  
Vol 552 ◽  
Author(s):  
P. Shang ◽  
R. Keyse ◽  
I. P Jones ◽  
R. E. Smallman
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Large Angle ◽  
Scanning Transmission Electron Microscope ◽  
Al Content ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Intense Electron Beams ◽  
Boundary Chemistry ◽  
Intense Electron

ABSTRACTScanning Transmission Electron Microscope (STEM) Energy Dispersive X-Ray analysis (EDX) linescans and mapping have been used to examine the large angle grain boundary chemistry of Ni-rich Ni3AI both with and without boron. The results show that the Al content is reduced while the Ni content is unchanged at the grain boundaries in all these alloys, with the percentage of reduction of Al at the grain boundaries decreasing as boron concentration increases. This is ascribed to differential surface sputtering of the lighter Al atoms.

High-resolution x-ray analysis of dislocation networks nn tilt boundaries

1988 ◽  
Vol 46 ◽  
pp. 612-613
Author(s):  
J. R. Michael ◽  
C. H. Lin ◽  
S. L. Sass
Keyword(s):  
Grain Boundaries ◽  
Analytical Electron Microscopy ◽  
Solute Segregation ◽  
X Ray ◽  
Periodic Arrays ◽  
Analytical Electron ◽  
Primary Dislocation ◽  
Tilt Boundaries ◽  
Polycrystalline Solids ◽  
Twist Boundaries

The segregation of solute atoms to grain boundaries in polycrystalline solids can be responsible for embrittlement of the grain boundaries. Although Auger electron spectroscopy (AES) and analytical electron microscopy (AEM) have verified the occurrence of solute segregation to grain boundaries, there has been little experimental evidence concerning the distribution of the solute within the plane of the interface. Sickafus and Sass showed that Au segregation causes a change in the primary dislocation structure of small angle [001] twist boundaries in Fe. The bicrystal specimens used in their work, which contain periodic arrays of dislocations to which Au is segregated, provide an excellent opportunity to study the distribution of Au within the boundary by AEM.The thin film Fe-0.8 at% Au bicrystals (composition determined by Rutherford backscattering spectroscopy), ∼60 nm thick, containing [001] twist boundaries were prepared as described previously. The bicrystals were analyzed in a Vacuum Generators HB-501 AEM with a field emission electron source and a Link Analytical windowless x-ray detector.

Application of analytical electron microscopy to studies of equilibrium and non-equilibrium segregation in materials

1992 ◽  
Vol 50 (2) ◽  
pp. 1214-1215
Author(s):  
Edward A Kenik
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Extended Defects ◽  
Probe Diameter ◽  
Specimen Holder ◽  
Analytical Electron ◽  
Scanning Transmission ◽  
Solute Atoms ◽  
Equilibrium Segregation ◽  
Non Equilibrium

Segregation of solute atoms to grain boundaries, dislocations, and other extended defects can occur under thermal equilibrium or non-equilibrium conditions, such as quenching, irradiation, or precipitation. Generally, equilibrium segregation is narrow (near monolayer coverage at planar defects), whereas non-equilibrium segregation exhibits profiles of larger spatial extent, associated with diffusion of point defects or solute atoms. Analytical electron microscopy provides tools both to measure the segregation and to characterize the defect at which the segregation occurs. This is especially true of instruments that can achieve fine (<2 nm width), high current probes and as such, provide high spatial resolution analysis and characterization capability. Analysis was performed in a Philips EM400T/FEG operated in the scanning transmission mode with a probe diameter of <2 nm (FWTM). The instrument is equipped with EDAX 9100/70 energy dispersive X-ray spectrometry (EDXS) and Gatan 666 parallel detection electron energy loss spectrometry (PEELS) systems. A double-tilt, liquid-nitrogen-cooled specimen holder was employed for microanalysis in order to minimize contamination under the focussed spot.

The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

1990 ◽  
Vol 48 (2) ◽  
pp. 442-443
Author(s):  
M. Tamizifar ◽  
G. Cliff ◽  
R.W. Devenish ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Argon Atmosphere ◽  
Age Hardening ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Analytical Electron ◽  
Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

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