Materials in Nuclear Energy Systems (MiNES) 2021: Fundamental Irradiation Damage- Session II
Program Organizers: Todd Allen, University of Michigan; Clarissa Yablinsky, Los Alamos National Laboratory; Anne Campbell, Oak Ridge National Laboratory
Tuesday 10:30 AM
November 9, 2021
Room: Allegheny
Location: Omni William Penn Hotel
Session Chair: Yongfeng Zhang, University of Wisconsin
10:30 AM Invited
Physical Understanding of Radiation Hardening of Neutron Irradiated FeCr Alloys: Cristelle Pareige1; A. Etienne1; P-M. Gueye1; M. Hernandez-Mayoral2; A. Ulbricht3; F. Bergner3; C. Heintze3; L. Malerba2; N. Castin4; G. Bonni4; M. J. Konstantinovic4; 1Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux; 2Materials of Energy Interest Division, Technology Department, CIEMAT, Avda. Complutense 40; 3Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf; 4SCKCEN, NMS institute
High-chromium ferritic-martensitic steels are promising candidates for structural components in Gen-IV and fusion reactors because of their excellent swelling resistance and good thermal properties. At low temperature, the operating window is limited by irradiation hardening and the correlated embrittlement. These are influenced by Cr content but also by impurity content (Ni, Si, P and C) and initial microstructure (ferritic vs martensitic). We investigated these factors in neutron irradiated Fe9Cr alloys and steels with advanced experimental techniques, including PAS, SANS, TEM, APT and mechanical testing. These experimental results are simulated and interpreted from the point of view of the physical mechanisms that drive the microstructure evolution using a physical model that also provides a quantitative prediction of the ensuing radiation hardening and embrittlement, bridging the formation of nano-sized solute clusters with hardening or embrittlement. This work is part of the H2020/M4F project and of the EERA/JPNM.
11:10 AM
The Kinetics and Stability of Alpha Prime (α’) Precipitates in FeCr Binary Alloy under Ion Irradiations: Yajie Zhao1; Arunodaya Bhattacharya2; Cristelle Pareige3; Caleb Massey2; Jonathan Poplawsky2; Pengcheng Zhu1; Jean Henry4; Steven Zinkle1; 1University of Tennessee Knoxville; 2Oak Ridge National Laboratory; 3Université et INSA de Rouen; 4CEA, DEN, Service de Recherches Métallurgiques Appliquées, Laboratoire d’Analyse Microstructurale des Matériaux, Université Paris-Saclay F-91191 Gif-sur-Yvette, France
Cr-enriched α’ precipitates severally degrade the mechanical property of FeCr based Ferritic-Martensitic steels. However, the kinetics and stability of α’ precipitation under higher dose rate ion irradiation conditions are not well understood. In this study, High purity Fe-(10-18%)Cr specimens in either solid solution state or pre-aged to form α’ precipitates were irradiated with 8 MeV Fe ions at 300-450 °C and 10-5-10-3 dpa/s to final doses of 0.37 or 3.7 dpa. The quantification of α’ precipitates after irradiations was performed with atom probe tomography (APT) located at ORNL's CNMS. The critical irradiation condition (temperature and dose rate) for α’ to form was found to be 300 °C and 10-3 dpa/s in Fe18Cr. At conditions where α’ were observed, the evolution of size and number density of precipitates follows an Ostwald ripening mechanism, the kinetics of which is modified by the irradiation dose rate and temperature.
11:30 AM
Effect of Cr and Temperature on Dislocation Loops in Heavy Ion Irradiated Ultra-high Purity FeCr Alloys: Yao Li1; Arunodaya Bhattacharya2; Ling Wang1; Yajie Zhao1; Steven Zinkle1; Jean Henry3; 1University of Tennessee Knoxville; 2Oak Ridge National Laboratory; 3The French Alternative Energies and Atomic Energy Commission
In Fe and Fe-Cr alloys, a/2<111> and a<100> type loops are observed after irradiations. In this study, we performed multi-temperature (300-450°C) irradiation using 8 MeV Fe ions (ion range of 2 μm) to midrange doses of ~0.35 and 3.5 dpa at dose rates of 10-5 and 10-4 dpa/s on Fe and Fe-xCr model alloys (x = 3- 18wt.%). Loop identification used a combination of conventional diffraction contrast TEM imaging techniques and the g∙b method. Nearly all loops were interstitial-type. We observed petal-shaped loop clusters in samples at 450 ℃ and 0.35 dpa. At 350℃ and 0.35 dpa, dislocations decorated by loops were the major phenomenon. At 350℃ and 3.5 dpa midrange dose, ½ <111> loop fraction increased with increasing irradiation depth, from16% in the near-surface region (0-300nm) to 81% in the beyond-damage region (2350-2600nm) in Fe. Mean loop diameter decreased from 20 nm to 7nm with Cr addition.