Preparation of in Situ Cu-Nb Composite Sheet and Wire for Tem Analysis

1987 ◽  
Vol 115 ◽  
Author(s):  
C. L. Trybus ◽  
F. C. Laabs ◽  
A. R. Pelton ◽  
V. A. Spitzig
Keyword(s):  
Electrochemical Techniques ◽  
Wire Drawing ◽  
Thick Sheet ◽  
Two Phase ◽  
Tem Analysis ◽  
Excessive Heat ◽  
Transmission Electron ◽  
Transmission Electron Microscopy Characterization ◽  
Microscopy Characterization

ABSTRACTCu-Nb in situ composites attain anomolous increases in strength upon mechanical deformation. The unique filamentary microstructures that evolve during processing (cold rolling and/or wire drawing) are the source of the strengthening. Results from transmission electron microscopy characterization studies have played a key role in the understanding of the relationships between structure and properties. However, the fabrication of reliable TEM samples has been extremely challenging for the following reasons: (1) traditional electrochemical techniques are not suitable for the two-phase microstructure, (2) preparation of longitudinal and transverse sections of fine (∼150 μm diameter wires) and thin (∼60 μm thick) sheet is tedious, and (3) it is necessary to avoid excessive heat (< 30°C) during sample preparation to preserve the metastable structural arrangements. This paper will review the procedures used to prepare TEM specimens from bulk wire and sheet samples as well as from extracted Nb filaments. Proper techniques for plating, mounting, sectioning, polishing, and ion-thinning will be discussed.

Growth of Epitaxial IrSi3 Layers on Si(111)

1989 ◽  
Vol 160 ◽  
Author(s):  
T. L. Lin ◽  
C. W. Nieh
Keyword(s):  
Surface Morphology ◽  
Molecular Beam ◽  
Solid Phase ◽  
Single Mode ◽  
Growth Conditions ◽  
Tem Analysis ◽  
Mbe Growth ◽  
Good Surface ◽  
Transmission Electron

AbstractEpitaxial IrSi3 films have been grown on Si (111) by molecular beam epitaxy (MBE) at temperatures ranging from 630 to 800 °C and by solid phase epitaxy (SPE) at 500 °C. Good surface morphology was observed for IrSi3 layers grown by MBE at temperatures below 680 °C, and an increasing tendency to form islands is noted in samples grown at higher temperatures. Transmission electron microscopy (TEM) analysis reveals that the IrSi3 layers grow epitaxially on Si(111) with three epitaxial modes depending on the growth conditions. For IrSi3 layers grown by MBE at 630 °C, two epitaxial modes were observed with ~ 50% area coverage for each mode. Single mode epitaxial growth was achieved at a higher MBE growth temperature, but with island formation in the IrSi3 layer. A template technique was used with MBE to improve the IrSi3 surface morphology at higher growth temperatures. Furthermore, single-crystal IrSi3 was grown on Si(111) at 500 °C by SPE, with annealing performed in-situ in a TEM chamber.

The Effect of Water Vapor on Oxidation Performance of Alloys Used in Recuperators

2002 ◽  
Author(s):  
Bruce A. Pint ◽  
Karren L. More ◽  
Peter F. Tortorelli
Keyword(s):  
Water Vapor ◽  
High Performance ◽  
Waste Heat ◽  
Alumina Scale ◽  
Effect Of Water ◽  
Transmission Electron ◽  
Transmission Electron Microscopy Characterization ◽  
Surface Oxides ◽  
Oxidation Performance ◽  
Microscopy Characterization

The use of a recuperator to recover waste heat from the exhaust gases is one method for improving a microturbine’s energy efficiency. This study looked at the effect of water vapor in the exhaust gas on the oxidation resistance of a current technology stainless steel and several high performance replacement alloys. Alloys of interest are high-Cr, Ni-base superalloys such as alloy 625 and aluminum-containing alloys such as Haynes alloy 214 and Plansee alloy PM2000, which is an oxide-dispersed FeCrAl. The latter two alloys form a protective external alumina scale which is more resistant to water vapor environments than chromia scales. Scanning and transmission electron microscopy characterization of the specimen surface oxides after laboratory exposures showed only minor effects of the addition of water vapor to the environment, which is consistent with the excellent corrosion resistance of these high performance alloys.

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