scholarly journals Insights into the Hydrogen‐Related Mechanism behind Defect Formation during Light‐ and Elevated‐Temperature‐Induced Degradation

2021 ◽  
pp. 2000584
Author(s):  
Benjamin Hammann ◽  
Lazhar Rachdi ◽  
Wolfram Kwapil ◽  
Florian Schindler ◽  
Martin C. Schubert
Keyword(s):  
Elevated Temperature ◽  
Defect Formation

In situ 64Cu Doppler-broadening positron-annihilation methods for elevated temperature study of defect formation in metals

1995 ◽  
Vol 73 (1-2) ◽  
pp. 11-17 ◽  
Author(s):  
D. W. Lawther ◽  
R. A. Dunlap
Keyword(s):  
Electrical Resistivity ◽  
Elevated Temperature ◽  
Positron Annihilation ◽  
Defect Structure ◽  
Elevated Temperatures ◽  
Defect Formation ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Spectroscopy Experiment

A Doppler-broadening positron-annihilation-spectroscopy experiment that utilizes an in situ 64Cu source for the study of Cu and Cu-containing materials is described. This technique is particularly useful for the investigation of defect structure at elevated temperatures, and the present instrumentation provides reliable results up to about 1000 °C. The method described is applicable to Cu-containing samples with as little as about 0.1 at.% Cu. Results from measurements on a single crystal of elemental Cu are compared with literature results obtained using other positron-annihilation methods and electrical-resistivity studies.

Evidence for a shear mechanism for the precipitation of γ-zirconium hydride in zirconium

1978 ◽  
Vol 36 (1) ◽  
pp. 658-659
Author(s):  
G.J.C. Carpenter
Keyword(s):  
Elevated Temperature ◽  
Strain Field ◽  
Zirconium Hydride ◽  
Zirconium Atom ◽  
Atom Diffusion ◽  
Solvus Temperature ◽  
Hexagonal Close Packed ◽  
Partial Dislocations ◽  
The Face

In zirconium-hydrogen alloys, rapid cooling from an elevated temperature causes precipitation of the face-centred tetragonal (fct) phase, γZrH, in the form of needles, parallel to the close-packed <1120>zr directions (1). With low hydrogen concentrations, the hydride solvus is sufficiently low that zirconium atom diffusion cannot occur. For example, with 6 μg/g hydrogen, the solvus temperature is approximately 370 K (2), at which only the hydrogen diffuses readily. Shears are therefore necessary to produce the crystallographic transformation from hexagonal close-packed (hep) zirconium to fct hydride.The simplest mechanism for the transformation is the passage of Shockley partial dislocations having Burgers vectors (b) of the type 1/3<0110> on every second (0001)Zr plane. If the partial dislocations are in the form of loops with the same b, the crosssection of a hydride precipitate will be as shown in fig.1. A consequence of this type of transformation is that a cumulative shear, S, is produced that leads to a strain field in the surrounding zirconium matrix, as illustrated in fig.2a.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

Xenon ion irradiation of superconducting YBa2Cu3O7 thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 92-93
Author(s):  
H. Watanabe ◽  
B. Kabius ◽  
B. Roas ◽  
K. Urban
Keyword(s):  
Defect Formation ◽  
Ion Irradiation ◽  
High Resolution Electron Microscopy ◽  
Structural Disorder ◽  
Flux Lines ◽  
Pinning Effect ◽  
Magnetic Flux Lines ◽  
Resolution Electron ◽  
Radiation Induced ◽  
Induced Defects

Recently it was reported that the critical current density(Jc) of YBa2Cu2O7, in the presence of magnetic field, is enhanced by ion irradiation. The enhancement is thought to be due to the pinning of the magnetic flux lines by radiation-induced defects or by structural disorder. The aim of the present study was to understand the fundamental mechanisms of the defect formation in association with the pinning effect in YBa2Cu3O7 by means of high-resolution electron microscopy(HRTEM).The YBa2Cu3O7 specimens were prepared by laser ablation in an insitu process. During deposition, a substrate temperature and oxygen atmosphere were kept at about 1073 K and 0.4 mbar, respectively. In this way high quality epitaxially films can be obtained with the caxis parallel to the <100 > SrTiO3 substrate normal. The specimens were irradiated at a temperature of 77 K with 173 MeV Xe ions up to a dose of 3.0 × 1016 m−2.

Defect formation in solids by decay of electronic excitations

1985 ◽  
Vol 147 (11) ◽  
pp. 523 ◽  
Author(s):  
M.I. Klinger ◽  
Ch.B. Lushchik ◽  
T.V. Mashovets ◽  
G.A. Kholodar' ◽  
M.K. Sheinkman ◽  
...  
Keyword(s):  
Defect Formation ◽  
Electronic Excitations

INFLUENCE OF THE LOCATION OF THE BASEBOARD JUMPER FOR FIRMWARE FOR DEFECT FORMATION IN CHAIN DRIVE SPROCKET FORGING

2020 ◽  
Author(s):  
I.A. Tserna ◽  
◽  
V.V. Bukhov ◽  
Keyword(s):  
Computer Simulation ◽  
Defect Formation ◽  
Chain Drive ◽  
Combine Harvester

The paper presents the results of computer simulation of the process of de-formationforged chain wheels, combine harvester; the influence of the placement of the jumper outline for firmware on the processes of defect formation in forging.

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