Atom Probe Tomography Characterization of High-Dose Ion Irradiated MA957

Journal Article · Sun Feb 28 23:00:00 EST 2021 · Journal of Nuclear Materials

DOI:https://doi.org/10.1016/j.jnucmat.2020.152528· OSTI ID:1756436

Wang, Jing ^[1]; Toloczko, Mychailo B. ^[1]; Voyevodin, V ^[2]; Bryk, V. V. ^[3]; Borodin, O. V. ^[4]; Melnichenko, V. V. ^[5]; Kalchenko, A S. ^[6]; Garner, Frank ^[7]; Shao, Lin ^[7]

---

1. BATTELLE (PACIFIC NW LAB)
2. Kharkov Institute of physics & Technology, Kharkov, Ukraine
3. NSC Kharkov Institute of Physics & Technology, Kharkov, Ukraine
4. NSC Kharkov Institute of Physics & Technology
5. Kharkov Institute of Physics and Technology, Kharkov, Ukraine
6. Institute of Solid State Physics-Kharkov, Ukraine
7. Texas A & M University

This paper presents a comprehensive characterization study of the microstructural responses to ion irradiation of the oxide dispersion strengthened (ODS) ferritic alloy MA957 using atom probe tomography (APT). The MA957 specimens were irradiated by 1.8 MeV Cr3+ ions to doses and temperatures relevant to advanced fast reactors (100 and 500 dpa at 400-500 °C). The average sizes of the YTiO particles decreased slightly after irradiation at all temperatures, with the most pronounced change at 400 °C. The particle number densities for 400 and 500 °C were slightly below number densities for the unirradiated condition, while the values were slightly higher at 420 and 450 °C. This behavior is consistent with the Nelson-Hudson-Mazey rate theory model that considers the competing effects between recombination and dissolution. An increase in the Y/Ti ratio of the YTiO particles was observed at the two lower temperatures. The formation of Cr-rich precipitates (a') was observed in specimens irradiated at temperatures up to 450 °C. Irradiation-induced segregation on grain boundaries was also investigated. Grain boundary element concentration profiles and ion maps demonstrate differences among the irradiation temperatures, with most datasets differing from the unirradiated condition. A key focus of this ion irradiation study is the high-dose response, and this quantitative assessment revealed relatively small but distinct effects of irradiation on microstructure evolution. Overall, these results showing minor second phase evolution suggest that MA957 should retain mechanical performance generally well up to 500 dpa for the irradiation temperatures studied.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1756436
• Report Number(s): PNNL-SA-151384
• Journal Information: Journal of Nuclear Materials, Journal Name: Journal of Nuclear Materials Vol. 545
• Country of Publication: United States
• Language: English