Near surface elemental concentration gradients in annealed 304 stainless steel as determined by analytical electron microscopy

1986 ◽  
Vol 25 (5-6) ◽  
pp. 397-407
Author(s):  
P. M. Fabis ◽  
B. S. Covino
Keyword(s):  
Electron Microscopy ◽  
Stainless Steel ◽  
Elemental Concentration ◽  
Analytical Electron Microscopy ◽  
304 Stainless Steel ◽  
Concentration Gradients ◽  
Near Surface ◽  
Analytical Electron

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 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.

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.

Precipitation at α/γ interfaces in duplex stainless steel

1992 ◽  
Vol 50 (1) ◽  
pp. 60-61
Author(s):  
M.G. Burke ◽  
E.A. Kenik
Keyword(s):  
Electron Microscopy ◽  
Stainless Steel ◽  
Grain Boundaries ◽  
Duplex Stainless Steel ◽  
Stainless Steels ◽  
Analytical Electron Microscopy ◽  
Nuclear Industry ◽  
Temperature Range ◽  
Α Phase ◽  
Analytical Electron

Duplex (austenite/ferrite) stainless steels are used in a variety of applications in the nuclear industry, particularly for coolant pipes, valves and pumps. These materials may become embrittled after prolonged ageing in the temperature range ∼350 - 550°C due to precipitation of G-phase, an FCC-based Ni silicide, and the formation of a Cr-rich α' phase in the ferrite. In addition to the intragranular G-phase precipitates, preferential precipitation of other phases is often observed at grain boundaries, particularly α/γ interfaces. In this examination, the precipitates formed in a Nb-containing duplex stainless steel have been identified using analytical electron microscopy.

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.

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