J. Mater. Sci. Technol. ›› 2026, Vol. 261: 94-102.DOI: 10.1016/j.jmst.2025.10.019

• Research article • Previous Articles     Next Articles

Evolution of NiMnSi clusters in RPV steel under proton irradiation

Bin Lia,1, Wenqing Jiab,1, Jianchao Penga,c, Wenqiang Wanga, Miao Fua, Qiwei Quanb, Jian Yinb, Xiangbing Liub,*, Hefei Huangd,*, Wenqing Liua,*   

  1. aInstitute of Materials, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China;
    bMaterial Engineering Technology Center, Suzhou Nuclear Power Research Institute, Suzhou 215004, China;
    cKey Laboratory of Microstructure, Shanghai University, Shanghai 200444, China;
    dShanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
  • Received:2025-06-13 Revised:2025-10-14 Accepted:2025-10-15 Published:2025-10-27 Online:2025-10-27
  • Contact: *E-mail addresses: liuxbing@cgnpc.com.cn (X. Liu), huanghefei@sinap.ac.cn (H. Huang), wqliu@staff.shu.edu.cn (W. Liu).
  • About author:1These authors contributed equally to this work.

Abstract: In this paper, the evolution of NiMnSi clusters in 16MND5 commercial RPV steel under proton irradiation at 563 K was investigated using atom probe tomography (APT) and transmission electron microscope (TEM). The APT results showed that only Cu-rich clusters appeared at the irradiation damage of 0.05 dpa. As the irradiation damage was increased, the elements of Ni, Mn, and Si were enriched at the same position as Cu-rich clusters, forming NiMnSiCu clusters. Cu-rich clusters catalyzed the nucleation of NiMnSi clusters. When irradiation damage increased to 1.62 dpa, the composition ratio of Ni, Mn, and Si elements in the NiMnSi clusters was closed to the chemical ratio of the G-phase (Ni16Mn6Si7). The TEM results showed that under the irradiation damage of 1.62 dpa, the NiMnSi clusters had the structure characteristics of the G-phase, which suggested that NiMnSi clusters in RPV steel would eventually evolve into G-phase under high irradiation damage.

Key words: G-phase, Proton irradiation, RPV steels, NiMnSi clusters, Atom probe tomography