Modified microstructures in proton irradiated dual phase 308L weldment filler material

Zhen Li, Xun Zhan, Xian Ming Bai, Shao Chun Lee, Weicheng Zhong, Benjamin J. Sutton, Brent J. Heuser

Research output: Contribution to journalArticlepeer-review


The effect of proton irradiation on the microstructure of δ ferrite—γ austenite mixed phase 308L filler material in a 508–304 dissimilar metal weldment was investigated over a depth of 0 to 10 µm. Ni–Si–Mn G-phase precipitates were observed with SEM and TEM in δ ferrite but not in γ austenite. Our density functional theory based calculations show that the G/Fe interface energy in δ-Fe is significantly lower than that in γ-Fe (0.35 versus 1.25 J/m2), which provides a thermodynamics-based explanation for our experimental observations of preferential formation of G-phase in δ ferrite. STEM-EDS, TEM dark field imaging, and diffraction patterns confirmed the Ni–Si–Mn enriched precipitates were G-phase precipitates with a stoichiometry of Mn6Ni16Si7. Intragranular voids and Ni–Si enriched clusters were observed in irradiated γ austenite. Additionally, Ni and Si segregation was observed along the void interfaces. In both cases, Ni–Si clusters and segregation to voids, selected area diffraction patterns did not reveal the existence of a second phase. Proton irradiation induced Cr depletion and Si and Ni enrichment at γ−γ austenite grain boundaries that was characterized with STEM/EDS.

Original languageEnglish (US)
Article number152825
JournalJournal of Nuclear Materials
StatePublished - May 2021


  • G-phase precipitation
  • Ni-Si enriched clustering
  • SA508-304L DMW
  • proton irradiation

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • General Materials Science
  • Nuclear Energy and Engineering


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