A preliminary investigation of high dose ion irradiation response of a lanthana-bearing nanostructured ferritic steel processed via spark plasma sintering

Type
Journal Article
Year of Publication
2017
Authors
Somayeh Pasebani
Indrajit Charit
Ankan Guria
Yaqiao Wu
Jatuporn Burns
Darryl P. Butt
James I. Cole
Lin Shao
Journal
Journal of Nuclear Materials
Volume
495
ISSN
0022-3115
Date Published
Jan. 1, 2017
Publisher
Elsevier B.V.
Abstract

A nanostructured ferritic steel with nominal composition of Fe-14Cr-1Ti-0.3Mo-0.5La2O3 (wt.%) was irradiated with Fe+2 ions at 475 °C for 100, 200, 300 and 400 dpa. Grain coarsening was observed for the samples irradiated for 200–400 dpa resulting in an increase of the average grain size from 152 nm to 620 nm. Growth of submicron grains at higher radiation doses is due to decreased pinning effect imparted by Cr-O rich nanoparticles (NPs) that underwent coarsening via Ostwald ripening. Dislocation density consistently increased with increasing irradiation dose at 300 and 400 dpa. The mean radius of lanthanum-containing nanoclusters (NCs) decreased and their number density increased above 200 dpa, which is likely due to solutes ejection caused by ballistic dissolution and irradiation-enhanced diffusion. Chromium, titanium, oxygen and lanthanum content of nanoclusters irradiated at 200 dpa and higher got reduced by almost half the initial value. The reduction in size of the nanoclusters accompanied with their higher number density and higher dislocation density led to significant radiation hardening with increasing irradiation dose.