Anomalous small-angle X-ray scattering (ASAXS) study of irradiation-induced nanostructure change in Fe-ion beam irradiated oxide dispersion-strengthened (ODS) steel

• Published in: Journal of nuclear materials 2020-01, Vol.528, p.151890, Article 151890
• Main Authors: Kumada, Takayuki, Oba, Yojiro, Motokawa, Ryuhei, Morooka, Satoshi, Tominaga, Aki, Tanida, Hajime, Shobu, Takahisa, Konno, Azusa, Ohwada, Kenji, Oono, Naoko, Ukai, Shigeharu
• Format: Article
• Language: English
• Subjects: Anomalous small-angle X-ray scattering; Chemical precipitation; Dispersion hardening steels; Ion beams; Ion-beam irradiation; Iron; Irradiation; Irradiation-induced structural change; Nanostructure; ODS steel; Oxide dispersion strengthening; Power law; Precipitates; Shoulder; Small angle X ray scattering; Steel; Thickness; X-ray scattering
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2019.151890

We have succeeded in observing Fe-ion-beam induced nanostructural change of MA956 oxide dispersion-strengthened (ODS) steel using anomalous small-angle X-ray scattering (ASAXS) diffractometry. The ASAXS curve shows a power-law scattering that follows the Porod’s law and an overlapped shoulder peak at the magnitude of scattering vector, Q, around 0.6 nm−1. As the X-ray energy approaches the absorption K-edge of Cr (5.990 keV), the intensity of the power-law scattering slightly decreases, but that of the shoulder peak remarkably increases. From these results, the power-law scattering is attributed to Cr-poor scatterers with a radius much larger than 5 nm, and the shoulder peak is attributed to Cr-rich α′ precipitates with a mean radius of 2.8 nm. After the ion-beam irradiation, intensity of the power-law scattering is nearly doubled, but the shoulder peak remains unchanged within an error of 2%. The latter result indicates that the irradiation-induced changes of radius and inter-precipitation distance of the α′ precipitates are smaller than 10%, and the change of their interface thickness is less than 0.5 nm. In this way, our ASAXS results guarantee an absence of irradiation-induced nanostructure change of specific kinds of precipitates together with statistical errors, while observing changes of other precipitates. •Our ASAXS enables to observe nanostructural change in steel by Fe-ion irradiation.•ASAXS intensity of Cr-poor scatterer was doubled by the irradiation.•In contrast, the irradiation didn’t change the scattering of α′precipitates at all.•Irradiation induces neither growth, suppression, nor interface modification of α’.