Atom probe tomography analysis of nanostructure evolution in Ni-Cr-Mo low alloy steel under neutron irradiation

다국어 초록 (Multilingual Abstract)

Ni-Cr-Mo low alloy steels are being considered as alternative materials to replace the Mn-Mo-Ni low alloy steels used in reactor pressure vessels in nuclear power plants, because of their higher strength and toughness. However, the neutron irradiation occurring during reactor operation causes degradation of Ni-Cr-Mo low alloy steel. In this study, irradiation-induced clusters in a Ni-Cr-Mo model alloy irradiated in the High-flux advanced neutron application reactor (HANARO) research reactor were investigated via Atom probe tomography (APT). The irradiated specimens showed irradiation-induced hardening and embrittlement. The neutron irradiation caused Si clustering, and these spherical clusters were homogeneously distributed within the matrix. Ni was also clustered at the Si clusters. However, the other elements did not clearly exhibit clustering behavior. Si and Ni atoms were also located at the dislocations. To quantify the nano-sized clusters, a method based on the Density-based spatial clustering of applications with noise (DBSCAN) algorithm was implemented. The total number of clusters was calculated to be ~7 × 10 -4 n/nm 3 and the average cluster radius was less than 2 nm. The APT approach was demonstrated to be well suited for discovering the irradiation defect structures.

참고문헌 (Reference)

1 L. T. Stephenson, "New techniques for the analysis of fine-scaled clustering phenomena within atom probe tomography(APT)data" 13 : 448-463, 2007

2 T. Toyama, "Irraidation-induced precipitates in a neutron irradiated 304stainless steel studied by three-dimensional atom probe" 418 : 62-68, 2011

3 K. H. Lee, "Evaluation of Microstructural parameters controlling cleavage fracture toughness in Mn-Mo-Ni low alloy steels" 565 : 158-164, 2013

4 Shin-Beom Choi, "Enhancement of master curve method for inhomogeneous material" 대한기계학회 26 (26): 2727-2734, 2012

5 T. Takeuchi, "Effects of chemical composition and dose on microstructure evolution and hardening of neutron irradiated reactor pressure vessel steels" 402 : 93-101, 2010

6 M. C. Kim, "Comparison of fracture properties in SA 508 Gr.3 and Gr.4N high strength low alloy steels for advanced pressure vessel materials" 131 : 60-65, 2015

7 G. -G. Lee, "Atomistic analysis of radiation-induced segregation in ionirradiated stainless steel 316" 60 : 47-52, 2015

8 M. K. Miller, "Atom Probe Tomography: Analysis at the atomic level" Kluwer Academic/Plenum Publishers 2000

9 E. A. Marquis, "Applications of atom-probe tomography to the characterisation of solute behaviours" 69 : 37-62, 2010

10 M. K. Miller, "APT characterization of high nickel RPV steels" 351 : 187-196, 2006

11 M. Ester, "A densitybased algorithm for discovering clusters in large spatial databases with noise" AAAI Press 226-231,