Wall Forum 2024




Unraveling HI-supersaturation in low-energy ion/plasma-irradiated W surfaces

Wall Forum
  • Datum: 13.03.2024
  • Uhrzeit: 15:30 - 16:30
  • Vortragender: Liang GAO
  • Institut für Energie- und Klimaforschung (PlasmaPhysik), Forschungszentrum Jülich
  • Ort: Zoom Meeting Room 1
  • Gastgeber: IPP
In the present work, H content and defect microstructures in the H supersaturated surface layer (HSSL) formed upon a fluence seriers were performed using 15N-1H nuclear reaction analysis (NRA) and transmission electron microscopy (TEM). H concenration up to 16 at.% in HSSL was record-breakingly observed. Detailed experimental insights guide us to the conclusive role of defect sinks (e.g., free surface and vacancy clusters, etc.) in absorbing W self-interstitial atoms and materializing temporary Frenkel pairs (t-FP) as H-decorated vacancy-type defects under low-energy H ion/plasma irradiation. Fundamental effects of mobile hydrogen in irradiated materials and the possibility of SSL formation in W materials under fusion reactor conditions are discussed. [mehr]

Advanced materials for fission and fusion energy: Nanostructured alloys, bcc-superalloys and high entropy alloys

Wall Forum
Energy applications from gas turbines to nuclear reactors demand increased operation temperatures for improved efficiencies and performance, alongside supporting deep-decarbonization & hydrogen generation. Advances in materials capability are a key enabling technology for the next-generation low-carbon energy applications needed to address the climate emergency. Metals reinforced by ordered intermetallic precipitates form a potent strategy for the development of high temperature strength alongside damage tolerance, which is central to the success of state-of the-art fcc nickel-based superalloys. Such a strategy is equally of interest within bcc systems, such as W, Ti or Fe, to access increased melting point and low cost/density. However, despite their promise, refractory metal ‘bcc-superalloys’ are yet to be commercialised. Here successes, challenges and opportunities for the nascent materials class of bcc-superalloys will be discussed, including titanium- and tungsten-based [1, 2]. Further, strategies for nanostructured alloys and high entropy alloys (HEAs) [3] will be introduced, with a focus on the ability for nano-scale interfaces to act as sinks for irradiation damage. [1] – http://dx.doi.org/10.1016/j.scriptamat.2017.06.038 [2] – https://doi.org/10.1016/j.apmt.2021.101014 [3] – https://doi.org/10.1016/j.actamat.2019.01.006 [mehr]

Positron annihilation studies of Eurofer97/ODS steels after helium ion implantation

Wall Forum
The talk reviews our positron annihilation studies performed on Eurofer97 steel and its ODS variant, performed in the last about 20 years. Various aspects of radiation environments foreseen for these materials were experimentally simulated via ion implantation and studied by a combination of non-destructive characterization techniques. The primary characterization tools in these studies were two techniques based on positron annihilation, namely positron annihilation lifetime spectroscopy (PALS) and Coincidence Doppler Broadening (CDB) technique. In addition to bulk studies utilizing conventional radioisotope positron sources, ion-implanted specimens were analysed using slow positron beams. This review summarizes the key findings of these techniques concerning the nature of the radiation resistance of EUROFER/ODS steels. [mehr]
Zur Redakteursansicht