Preparation of Backthinned Ceramic Specimens

1985 ◽  
Vol 43 ◽  
pp. 182-183
Author(s):  
A. T. Fisher ◽  
P. Angelini
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Vacuum System ◽  
Back Surface ◽  
Surface Microstructure ◽  
Ion Milling ◽  
Near Surface ◽  
Depth Profiles ◽  
Analytical Electron ◽  
Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

Analytical electron microscopy of SiC implanted with Cr ions

1984 ◽  
Vol 42 ◽  
pp. 416-417
Author(s):  
P. S. Sklad ◽  
P. Angelini ◽  
C. J. McHargue ◽  
J. M. Williams
Keyword(s):  
Electron Microscopy ◽  
Depth Distribution ◽  
Analytical Electron Microscopy ◽  
Surface Microstructure ◽  
Polycrystalline Specimen ◽  
Near Surface ◽  
Ambient Temperatures ◽  
Chromium Ions ◽  
Analytical Electron ◽  
Post Implantation

Silicon carbide is an attractive structural material for high temperature applications that require chemical stability in aggressive environments and wear resistance. In order to investigate ion implantation as a means of improving surface properties, specimens of SiC were implanted with chromium ions. The present work is concerned with characterizing the near-surface microstructure produced by implantation and monitoring changes which occur during post-implantation annealing.A polycrystalline specimen of α SiC, pressureless sintered with boron additions by the Carburundum Co., was implanted with chromium ions at ambient temperatures. In order to obtain a broad fairly uniform depth distribution a multiple-energy implant schedule was employed: 4.03 x 1015 Cr ions/cm2 were implanted at 95 keV, 7.26 x 1015 Cr ions/cm2 were implanted at 190 kev, and 10 x 1015 Cr ions/cm2 were implanted at 280 keV.

Analytical Electron Microscopy of Ion-Implanted Metals

1985 ◽  
Vol 43 ◽  
pp. 282-285
Author(s):  
D.I. Potter ◽  
M. Ahmed ◽  
K. Ruffing
Keyword(s):  
Electron Microscopy ◽  
Ion Implantation ◽  
Friction And Wear ◽  
Analytical Electron Microscopy ◽  
Chemical Compositions ◽  
Surface Chemical ◽  
Near Surface ◽  
The Past ◽  
Analytical Electron ◽  
Property Changes

Ion implantation, used extensively for the past decade in fabricating semiconductor devices, now provides a unique means for altering the near-surface chemical compositions and microstructures of metals. These alterations often significantly improve physical properties that depend on the surface of the material; for example, catalysis, corrosion, oxidation, hardness, friction and wear. Frequently the mechanisms causing these beneficial alterations and property changes remain obscure and much of the current research in the area of ion implantation metallurgy is aimed at identifying such mechanisms. Investigators thus confront two immediate questions: To what extent is the chemical composition changed by implantation? What is the resulting microstructure? These two questions can be investigated very fruitfully with analytical electron microscopy (AEM), as described below.

Phase Identification in TiB2-Ni Composites by Analytical Electron Microscopy

1981 ◽  
Vol 39 ◽  
pp. 138-139
Author(s):  
P. S. Sklad ◽  
J. Bentley ◽  
A. T. Fisher ◽  
G. L. Lehman
Keyword(s):  
Electron Microscopy ◽  
Cutting Tools ◽  
Analytical Electron Microscopy ◽  
High Hardness ◽  
Phase Identification ◽  
Second Phase ◽  
Binder Phase ◽  
Ion Milling ◽  
X Ray ◽  
Analytical Electron

The transition metal diboride TiB2 is characterized by high hardness and high melting point (3253 K) . These properties make this material attractive for applications such as valve components in coal liquefaction plants and cutting tools. Liquid phase hot pressing using nickel as the fluidizing medium allows densification at lower temperatures than when using TiB2 powders alone, but the nickel and TiB2 react to form a complex multiphase microstructure. The purpose of this investigation was to identify the nickel-rich binder phase. The material examined was taken from a cylindrical compact hot pressed at ∼1720 K. During pressing most of the original 15 mol % Ni exuded from the initial mixtures. Specimens 3 mm dia were prepared for analytical electron microscopy (AEM) examination by mechanical lapping followed by ion milling.A typical microstructure of the TiB2-Ni composite examined at 120 kv by conventional transmission electron microscopy (TEM) is shown in Fig. 1. The microstructure is characterized by TiB2 grains bonded by a second phase which was observed at multiple grain intersections. X-ray energy dispersive spectroscopy (EDS) measurements were made using a Philips EM400T/FEG. probe sizes of ∼10 nm dia and probe currents of ∼5 nA were used so that measurements could be made in thin regions of the binder phase, where beam broadening was small. Typical x-ray spectra from an intergranular region and an adjacent TiB2 grain are shown in Fig. 2. The results of standardless quantitative analyses of binder phase spectra indicated a composition (for Z > 11) of at least 95% Ni.

An Analytical Electron Microscopy Characterization of Melt-Spun Iron/Rare-Earth/Boron Magnetic Materials

1985 ◽  
Vol 58 ◽  
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless ◽  
G.C. Hadjiipanayis
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Rare Earth ◽  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
High Energy ◽  
Ion Milling ◽  
Analytical Electron ◽  
Strategic Element ◽  
Microscopy Characterization

Iron/rare-earth/boron permanent magnet materials have recently been delveloped to reduce the need for the strategic element cobalt, which was previously the primary canponent of high-energy magnets. These materials are generally produced by annealing rapidly solidified ribbons or by conventional powder metallurgy techniques. This paper will report results from an analytical electron microscopy characterization undertaken to establish the relationship between the magnetic properties and the microstructure of two iron/rare-earth/boron (Fe/RE/B) alloys. Ribbons of Fe75Pr15B10 and Fe77Tb15B8 were produced by melt-spinning. To obtain optimum magnetic properties, both alloys were then annealed at 700°C, the FePrB ribbons for 6 minutes and the FeTbB ribbons for 90 minutes. Foils for transmission electron microscopy were prepared by ion-milling the ribbons on a cold stage and examined using a Philips 400T TEM/STEM equipped with an energy dispersive x-ray unit.

Analytical Electron Microscopy of α-Al2O3 implanted with iron

1987 ◽  
Vol 45 ◽  
pp. 146-147
Author(s):  
P. S. Sklad
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Analytical Electron Microscopy ◽  
Microstructural Development ◽  
Near Surface ◽  
Analytical Electron ◽  
Α Al2o3 ◽  
Fe Ions ◽  
Post Implantation ◽  
Flowing Oxygen

Ion implantation has become an accepted method for achieving a wide variation in the near surface microstructure and properties of many materials. A number of recent studies have concentrated on modifying the properties of Al2O3. However, the effectiveness of such surface modification is strongly dependent on the microstructural development which takes place in the implanted region during post-implantation annealing. Analytical electron microscopy (AEM) techniques are unique in that they allow direct observation of changes in microstructure and composition which are produced during such anneals.Single crystals of α-Al2O3 in the basal orientation were implanted with 160 keV Fe ions to a dose of 4 x 1016 or 1 x 1017 ions/cm2 with a dose rate of ∼2 amps/cm2. The implantations were carried out at room temperature. A number of specimens were subsequently annealed for 1 h at temperatures in the range 973 K to 1773 K in flowing oxygen.

Application of Analytical Electron Microscopy to Ion Implantation and Near Surface Microstructures

1985 ◽  
Vol 62 ◽  
Author(s):  
P. S. Sklad
Keyword(s):  
Electron Microscopy ◽  
Ion Implantation ◽  
Ion Beam ◽  
Analytical Electron Microscopy ◽  
Theoretical Models ◽  
Solute Concentration ◽  
Specimen Preparation ◽  
Second Phase ◽  
Near Surface ◽  
Analytical Electron

ABSTRACTSurface modification using ion beam techniques is recognized as an important method for improving surface controlled properties of metallic, ceramic, and semiconductor materials. Determination of the microstructure and composition in regions located within a few hundred nanometers of the surface is essential to gaining an understanding of the mechanisms responsible for the improved properties. Analytical electron microscopy (AEM), high resolution microscopy, and microdiffraction are ideally suited for this purpose. These techniques are powerful tools for characterizing microstructure in terms of solute concentration profiles, second phase formation, lattice damage, crystallinity of the implanted layer and annealing behavior. Such analyses allow correlations with theoretical models, property measurements and results of complementary techniques. The proximity of the regions of interest to the surface also places stringent requirements on specimen preparation techniques. The power of AEM in examining the effects of ion implantation will be illustrated by reviewing the results of several investigations. A brief discussion of some important aspects of specimen preparation will also be included.

Analytical Electron Microscopy of Precipitates in Ion-Implanted Mgal2O4 Spinel

1994 ◽  
Vol 373 ◽  
Author(s):  
N. D. Evans ◽  
S. J. Zinkle ◽  
J. Bentley
Keyword(s):  
Electron Microscopy ◽  
Energy Loss ◽  
Volume Fraction ◽  
Analytical Electron Microscopy ◽  
Metallic Aluminum ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Analytical Electron ◽  
Electron Energy Loss ◽  
Ion Implanted

AbstractAnalytical electron microscopy (AEM) has been used to investigate precipitates in MgAl2O4 spinel implantated with Al+, Mg+, or Fe2+ ions. Experiments combining diffraction, energy dispersive X-ray spectrometry (EDS), electron energy-loss spectrometry (EELS), and energy-filtered imaging were employed to identify and characterize precipitates observed in the implanted ion region. Diffraction studies suggested these are metallic aluminum colloids, although EELS and energy-filtered images revealed this to be so only for the Al+ and Mg+ implantations, but not for Fe2+ ion implantations. Multiple-least-squares (MLS) fitting of EELS plasmon spectra was employed to quantify the volume fraction of metallic aluminum in the implanted ion region. Energy-filtered plasmon images of the implanted ion region clearly show the colloid distribution in the Al+ and Mg+ implanted spinel. Energy-filtered images from the Fe2+ ion implanted spinel indicate that the features visible in diffraction contrast cannot be associated with either metallic aluminum or iron-rich precipitates.

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