MX precipitate behavior in an irradiated advanced Fe-9Cr steel: Helium effects on phase stability

T. M.Kelsy Green; Tim Graening; Weicheng Zhong; Ying Yang; Kevin G. Field

doi:10.1016/j.actamat.2025.121202

MX precipitate behavior in an irradiated advanced Fe-9Cr steel: Helium effects on phase stability

T. M.Kelsy Green, Tim Graening, Weicheng Zhong, Ying Yang, Kevin G. Field

Research output: Contribution to journal › Article › peer-review

Abstract

As part of an ongoing series aimed at optimizing Fe-9Cr reduced activation ferritic/martensitic (RAFM) alloys for fusion energy systems, this study explores MX precipitate behavior under dual-ion irradiations, specifically examining correlations between helium transmutation and irradiation-induced damage. Utilizing single and dual-beam ion irradiation, the research explores the combined effects of helium (10–25 appm He/dpa), temperature (400–600 °C), and damage levels (15–100 dpa) on the microstructural evolution of CNA9 steel, a variant of Castable Nanostructured Alloys (CNAs). The study demonstrates that helium co-implantation hinders radiation-enhanced coarsening of MX-TiC precipitates at 500 and 600 °C, maintaining MX-TiC precipitate stability at moderate damage levels (15 dpa) but failing to prevent complete precipitate dissolution at higher damage levels (≥50 dpa) when irradiated at 500 °C. A generalized precipitate stability model suggests that helium-induced suppression of diffusion alters the balance between recoil resolution and back diffusion for MX-TiC precipitates, enhancing the current understanding of precipitate behavior under damage and transmutation simulated dual-ion irradiation conditions.

Original language	English
Article number	121202
Journal	Acta Materialia
Volume	296
DOIs	https://doi.org/10.1016/j.actamat.2025.121202
State	Published - Sep 1 2025

Funding

The experimental work presented here was funded by the Fusion Energy Sciences program (DOE-FOA-0002173). The authors also acknowledge the University of Michigan-Ann Arbor College of Engineering for financial support and the Michigan Center for Materials Characterization for use of the instruments and staff assistance. Research presented here was also partially supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project number XXPV. This research was partly sponsored by the US Department of Energy, Office of Fusion Energy Sciences under contract DE-AC05–00OR22725 with UT-Battelle, LLC.

Keywords

Characterization
Dual ion irradiation
Fusion materials
Helium irradiation
High temperature
Ion irradiation
MX precipitates
Nuclear materials
Phase stability
Steel
TEM

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10.1016/j.actamat.2025.121202

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title = "MX precipitate behavior in an irradiated advanced Fe-9Cr steel: Helium effects on phase stability",

abstract = "As part of an ongoing series aimed at optimizing Fe-9Cr reduced activation ferritic/martensitic (RAFM) alloys for fusion energy systems, this study explores MX precipitate behavior under dual-ion irradiations, specifically examining correlations between helium transmutation and irradiation-induced damage. Utilizing single and dual-beam ion irradiation, the research explores the combined effects of helium (10–25 appm He/dpa), temperature (400–600 °C), and damage levels (15–100 dpa) on the microstructural evolution of CNA9 steel, a variant of Castable Nanostructured Alloys (CNAs). The study demonstrates that helium co-implantation hinders radiation-enhanced coarsening of MX-TiC precipitates at 500 and 600 °C, maintaining MX-TiC precipitate stability at moderate damage levels (15 dpa) but failing to prevent complete precipitate dissolution at higher damage levels (≥50 dpa) when irradiated at 500 °C. A generalized precipitate stability model suggests that helium-induced suppression of diffusion alters the balance between recoil resolution and back diffusion for MX-TiC precipitates, enhancing the current understanding of precipitate behavior under damage and transmutation simulated dual-ion irradiation conditions.",

keywords = "Characterization, Dual ion irradiation, Fusion materials, Helium irradiation, High temperature, Ion irradiation, MX precipitates, Nuclear materials, Phase stability, Steel, TEM",

author = "Green, \{T. M.Kelsy\} and Tim Graening and Weicheng Zhong and Ying Yang and Field, \{Kevin G.\}",

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doi = "10.1016/j.actamat.2025.121202",

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T1 - MX precipitate behavior in an irradiated advanced Fe-9Cr steel

T2 - Helium effects on phase stability

AU - Green, T. M.Kelsy

AU - Graening, Tim

AU - Zhong, Weicheng

AU - Yang, Ying

AU - Field, Kevin G.

PY - 2025/9/1

Y1 - 2025/9/1

N2 - As part of an ongoing series aimed at optimizing Fe-9Cr reduced activation ferritic/martensitic (RAFM) alloys for fusion energy systems, this study explores MX precipitate behavior under dual-ion irradiations, specifically examining correlations between helium transmutation and irradiation-induced damage. Utilizing single and dual-beam ion irradiation, the research explores the combined effects of helium (10–25 appm He/dpa), temperature (400–600 °C), and damage levels (15–100 dpa) on the microstructural evolution of CNA9 steel, a variant of Castable Nanostructured Alloys (CNAs). The study demonstrates that helium co-implantation hinders radiation-enhanced coarsening of MX-TiC precipitates at 500 and 600 °C, maintaining MX-TiC precipitate stability at moderate damage levels (15 dpa) but failing to prevent complete precipitate dissolution at higher damage levels (≥50 dpa) when irradiated at 500 °C. A generalized precipitate stability model suggests that helium-induced suppression of diffusion alters the balance between recoil resolution and back diffusion for MX-TiC precipitates, enhancing the current understanding of precipitate behavior under damage and transmutation simulated dual-ion irradiation conditions.

AB - As part of an ongoing series aimed at optimizing Fe-9Cr reduced activation ferritic/martensitic (RAFM) alloys for fusion energy systems, this study explores MX precipitate behavior under dual-ion irradiations, specifically examining correlations between helium transmutation and irradiation-induced damage. Utilizing single and dual-beam ion irradiation, the research explores the combined effects of helium (10–25 appm He/dpa), temperature (400–600 °C), and damage levels (15–100 dpa) on the microstructural evolution of CNA9 steel, a variant of Castable Nanostructured Alloys (CNAs). The study demonstrates that helium co-implantation hinders radiation-enhanced coarsening of MX-TiC precipitates at 500 and 600 °C, maintaining MX-TiC precipitate stability at moderate damage levels (15 dpa) but failing to prevent complete precipitate dissolution at higher damage levels (≥50 dpa) when irradiated at 500 °C. A generalized precipitate stability model suggests that helium-induced suppression of diffusion alters the balance between recoil resolution and back diffusion for MX-TiC precipitates, enhancing the current understanding of precipitate behavior under damage and transmutation simulated dual-ion irradiation conditions.

KW - Characterization

KW - Dual ion irradiation

KW - Fusion materials

KW - Helium irradiation

KW - High temperature

KW - Ion irradiation

KW - MX precipitates

KW - Nuclear materials

KW - Phase stability

KW - Steel

KW - TEM

UR - https://www.scopus.com/pages/publications/105009230998

U2 - 10.1016/j.actamat.2025.121202

DO - 10.1016/j.actamat.2025.121202

M3 - Article

AN - SCOPUS:105009230998

SN - 1359-6454

VL - 296

JO - Acta Materialia

JF - Acta Materialia

M1 - 121202

ER -

MX precipitate behavior in an irradiated advanced Fe-9Cr steel: Helium effects on phase stability

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