Microstructural analysis of impurity segregation around β-Nb precipitates in Zr–Nb alloy using positron annihilation spectroscopy and atom probe tomography

2015 ◽  
Vol 108 ◽  
pp. 156-159 ◽  
Author(s):  
T. Toyama ◽  
Y. Matsukawa ◽  
K. Saito ◽  
Y. Satoh ◽  
H. Abe ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Atom Probe Tomography ◽  
Microstructural Analysis ◽  
Positron Annihilation Spectroscopy ◽  
Atom Probe ◽  
Impurity Segregation

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

Sign in / Sign up

Export Citation Format

Share Document