On the Behavior of Yttria/Yttrium during Mechanical Alloying of a Fe - Y2O3 Model Alloy System

2014 ◽  
Vol 922 ◽  
pp. 598-603
Author(s):  
Gerald Ressel ◽  
Peter Parz ◽  
Alexander Fian ◽  
David Holec ◽  
Sophie Primig ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Positron Annihilation ◽  
Photoelectron Spectroscopy ◽  
Atom Probe Tomography ◽  
Elevated Temperatures ◽  
Positron Annihilation Spectroscopy ◽  
Atom Probe ◽  
Model Alloy ◽  
High Temperature Strength ◽  
X Ray

Mechanical alloying (MA) is an established way to prepare nanocrystalline materials and metastable solutions of materials, which normally have no mutual solubility. This is also the case for oxide dispersion strengthened (ODS) steels with improved mechanical properties at elevated temperatures. It is known that a small addition of yttria (Y2O3) has a beneficial effect on high temperature strength and reduces the creep rate in mechanically alloyed ferritic steels by about six orders of magnitude. In this work we present an experimental study using atom probe tomography, X-ray photoelectron spectroscopy, and positron annihilation spectroscopy combined with first principles modeling focusing on the distribution and behavior of yttria in pure iron prepared by mechanical alloying. Atom probe tomography and X-ray photoelectron spectroscopy measurements as well as positron annihilation spectroscopy conducted on powder particles directly after milling have revealed that a predominantly fraction of the yttria powder dissolves in the iron matrix and Y atoms occupy convenient positions, such as vacancies or dislocations. This is supported by ab initio calculations demonstrating that the formation energy for Y substitutional defects in bcc-Fe is significantly lower in the close neighborhood of vacancies.

Positron Annihilation Study of Neutron-Irradiated Nuclear Reactor Pressure Vessel Steels and their Model Alloy: Effect of Purity on the Post-Irradiation Annealing Behavior

2012 ◽  
Vol 733 ◽  
pp. 257-263 ◽  
Author(s):  
Akira Kuramoto ◽  
Yasuyoshi Nagai ◽  
T. Toyama ◽  
T. Takeuchi ◽  
M. Hasegawa
Keyword(s):  
Positron Annihilation ◽  
First Generation ◽  
Nuclear Reactor ◽  
Positron Annihilation Spectroscopy ◽  
Atom Probe ◽  
Model Alloy ◽  
Annealing Behavior ◽  
Post Irradiation ◽  
Alloy Effect ◽  
Positron Annihilation Study

Post-irradiation annealing (PIA) behavior of irradiation-induced microstructural changes and hardening of two kind of A533B (first generation (1stGENS: 0.16 wt.% Cu) and second generation (2ndGENS: 0.04 wt.% Cu)) steels after neutron-irradiation of 3.9 × 1019 n cm–2 at 290 °C has been studied by positron annihilation spectroscopy, atom probe tomography and Vickers microhardness measurements. In the 1stGENS, clear two recovery stages are observed: (i) as-irradiated state to 450 °C and (ii) 450 to 600 °C. The first stage is due to annealing out of the most of irradiation-induced vacancy-related defects (VRDs), and the second stage corresponds to dissolving irradiation-induced Cu-rich solute nano-clusters (CRSCs). The experimental hardening is almost twice of the hardening due to the CRSCs estimated by Russell-Brown model below 350 °C, but almost the same as the estimation from 400 to 550 °C. In the 2ndGENS, the VRDs and non-Cu-rich solute nano-clusters (NCRSCs) recover at 450 °C. No CRSC has been formed even in all the annealing process. The experimental hardening is almost twice of the hardening estimated due to the NCRSCs by Russell-Brown model below 400 °C.

scholarly journals Atom-probe Tomography, Small Angle Neutron Scattering, Transmission Electron Microscopy, Positron Annihilation Spectroscopy and X-ray Absorption Spectroscopy Characterization of Nano-scale Features in Nanostructured Ferritic Alloys

2009 ◽  
Vol 15 (S2) ◽  
pp. 244-245 ◽  
Author(s):  
GR Odette ◽  
NJ Cunningham ◽  
EA Marquis ◽  
S Lozano-Perez ◽  
V de Castro ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Atom Probe Tomography ◽  
Small Angle Neutron Scattering ◽  
Positron Annihilation Spectroscopy ◽  
Atom Probe ◽  
Ferritic Alloys ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Revealing the interface nature of ZDDP tribofilm by X-ray photoelectron spectroscopy and atom probe tomography

2020 ◽  
Vol 72 (7) ◽  
pp. 923-930
Author(s):  
Chia-Jui Hsu ◽  
Jenifer Barrirero ◽  
Rolf Merz ◽  
Andreas Stratmann ◽  
Hisham Aboulfadl ◽  
...  
Keyword(s):  
Peer Review ◽  
Photoelectron Spectroscopy ◽  
Atom Probe Tomography ◽  
Steel Substrate ◽  
Atom Probe ◽  
Engine Oil ◽  
Content Type ◽  
X Ray ◽  
Sliding Test ◽  
Cylindrical Roller

Purpose To decrease wear and friction, zinc dialkyldithiophosphate (ZDDP) has been used in engine oil for several decades, but the mechanism of the tribofilm formation is still unclear. The purpose of this study is to characterize the chemical details of the tribofilm by using high-resolution approaching. Design/methodology/approach An ISO VG 100 mineral oil mixed with ZDDP was used in sliding tests on cylindrical roller bearings. Tribofilm formation was observed after 2 h of the sliding test. X-ray photoelectron spectroscopy (XPS) and atom probe tomography (APT) were used for chemical analysis of the tribofilm. Findings The results show that the ZDDP tribofilm consists of the common ZDDP elements along with iron oxides. A considerable amount of zinc and a small amount of sulfur were observed. In particular, an oxide interlayer with sulfur enrichment was revealed by APT between the tribofilm and the steel substrate. The depth profile of the chemical composition was obtained, and a tribofilm of approximately 40 nm thickness was identified by XPS. Originality/value A sulfur enrichment at the interface is observed by APT, which is beneath an oxygen enrichment. The clear evidence of the S interlayer confirms the hard and soft acids and bases principle. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0035/

scholarly journals Mapping nitrogen heteroatoms in carbon fibres using atom probe tomography and photoelectron spectroscopy

Carbon ◽  
2021 ◽  
Author(s):  
Marcus Johansen ◽  
Christoph Schlueter ◽  
Pui Lam Tam ◽  
Leif E. Asp ◽  
Fang Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Carbon Fibres

Oxidation of Alloy-X in Subcritical, Transition, and Supercritical Water

CORROSION ◽  
10.5006/3881 ◽  
2021 ◽  
Author(s):  
Zachary Karmiol ◽  
Dev Chidambaram
Keyword(s):  
Supercritical Water ◽  
Photoelectron Spectroscopy ◽  
Focused Ion Beam ◽  
Elevated Temperatures ◽  
Subcritical Water ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Based Superalloy ◽  
Before And After

This work investigates the oxidation of a nickel based superalloy, namely Alloy X, in water at elevated temperatures: subcritical water at 261°C and 27 MPa, the transition between subcritical and supercritical water at 374°C and 27 MPa, and supercritical water at 380°C and 27 MPa for 100 hours. The morphology of the sample surfaces were studied using scanning electron microscopy coupled with focused ion beam milling, and the surface chemistry was investigated using X-ray diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy before and after exposure studies. Surfaces of all samples were identified to comprise of a ferrite spinel containing aluminum.

scholarly journals The effect of cobalt on morphology, structure, and ORR activity of electrospun carbon fibre mats in aqueous alkaline environments

2021 ◽  
Vol 12 ◽  
pp. 1173-1186
Author(s):  
Markus Gehring ◽  
Tobias Kutsch ◽  
Osmane Camara ◽  
Alexandre Merlen ◽  
Hermann Tempel ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Elevated Temperatures ◽  
Current Collector ◽  
Alkaline Media ◽  
Emission Spectrometry ◽  
Free Standing ◽  
X Ray ◽  
Turbostratic Carbon ◽  
Current Densities

An innovative approach for the design of air electrodes for metal–air batteries are free-standing scaffolds made of electrospun polyacrylonitrile fibres. In this study, cobalt-decorated fibres are prepared, and the influence of carbonisation temperature on the resulting particle decoration, as well as on fibre structure and morphology is discussed. Scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental analysis, and inductively coupled plasma optical emission spectrometry are used for characterisation. The modified fibre system is compared to a benchmark system without cobalt additives. Cobalt is known to catalyse the formation of graphite in carbonaceous materials at elevated temperatures. As a result of cobalt migration in the material the resulting overall morphology is that of turbostratic carbon. Nitrogen removal and nitrogen-type distribution are enhanced by the cobalt additives. At lower carbonisation temperatures cobalt is distributed over the surface of the fibres, whereas at high carbonisation temperatures it forms particles with diameters up to 300 nm. Free-standing, current-collector-free electrodes assembled from carbonised cobalt-decorated fibre mats display promising performance for the oxygen reduction reaction in aqueous alkaline media. High current densities at an overpotential of 100 mV and low overpotentials at current densities of 333 μA·cm−2 were found for all electrodes made from cobalt-decorated fibre mats carbonised at temperatures between 800 and 1000 °C.

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