Title: Effects of helium on irradiation response of reduced-activation ferritic-martensitic steels: Using nickel isotopes to simulate fusion neutron response

Abstract

Understanding the effects of helium on microstructures and mechanical properties of reduced-activation ferritic-martensitic steels is important to use of these steels in fusion reactor structures. The 9Cr-2WVTa steels were doped with 58Ni and 60Ni isotopes at 2 weight percent to control the rate of transmutation helium generation. The samples were irradiated in the High Flux Isotope Reactor to ~24 displacements per atom at nominal temperatures of 300, 400, and 500°C, producing 228 and 7 atomic parts-per-million helium in the ⁵⁸Ni- and ⁶⁰Ni-doped samples, respectively. Transmission electron microscopy revealed a variety of precipitates and the radiation-induced dislocation loops and cavities (voids or helium bubbles). Tensile tests of the irradiated samples at the irradiation temperatures showed radiation-induced hardening at 300°C and radiation-induced softening at 400°C. Analysis indicates that the hardening primarily originated from the loops and cavities. The ⁵⁸Ni-doped samples had greater strengthening contributions from loops and cavities, leading to higher hardening with lower ductility than the ⁶⁰Ni-doped samples. The greater helium production of ⁵⁸Ni did not show pronounced reductions in ductility of the samples.

Authors:

Kim, B. K.  ^[1];

• Search DOE PAGES for author "Kim, B. K."
• Search DOE PAGES for ORCID "0000-0002-5392-5862"

Tan, L.  ^[1];

• Search DOE PAGES for author "Tan, L."
• Search DOE PAGES for ORCID "0000-0002-3418-2450"

Sakasegawa, H.  ^[2];

• Search DOE PAGES for author "Sakasegawa, H."
• Search DOE PAGES for ORCID "0000-0002-4241-1292"

Parish, C. M. ^[1]; Zhong, W. ^[1]; Tanigawa, H. ^[3]; Katoh, Y. ^[1]

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Japan Atomic Energy Agency, Okayama (Japan)
3. National Institutes for Quantum and Radiological Science and Technology (Japan)

Publication Date:

Mon Mar 01 00:00:00 EST 2021

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1760135

Alternate Identifier(s):

OSTI ID: 1776039

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Nuclear Materials

Additional Journal Information:

Journal Volume: 545; Journal Issue: n/a; Journal ID: ISSN 0022-3115

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Neutron irradiation; Microstructures; Dislocation loops; Precipitates; Radiation-induced hardening and softening