TY - JOUR
T1 - Early-stage microstructural evolution and phase stability in neutron-irradiated ferritic-martensitic steel T91
AU - Yan, Huan
AU - Liu, Xiang
AU - He, Lingfeng
AU - Stubbins, James
N1 - Funding Information:
This work was funded by the U.S. Department of Energy office of Nuclear Energy's Nuclear Energy University Program (NEUP) under Contract No. DOE INL 00127139 . The neutron irradiation experiments at the Advanced Test Reactor (ATR) were supported by Nuclear Science User Facilities (NSUF) award 08-92 . The post-irradiation experiments were conducted at the Microscopy and Characterization Suite (MaCS), Center for Advanced Energy Studies (NSUF access only project 15-8312 ) and were supported by the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-051D14517 as part of a Nuclear Science User Facilities experiment. The authors would like to acknowledge the training and support from MaCS staff Yaqiao Wu, Jatuporn Burns, Megha Dubey, and Joanna Taylor.
Publisher Copyright:
© 2021
PY - 2021/12/15
Y1 - 2021/12/15
N2 - A Fe-9Cr ferritic martensitic (F/M) steel T91 was neutron-irradiated in the Advanced Test Reactor up to 3.96 dpa in two temperature ranges, 466 °C to 534 °C and 571 °C to 632 °C. The microstructure evolution including dislocation loops, precipitation, segregation of elements and phase stability were studied using analytical scanning-transmission electron microscopy and atom probe tomography. The hardening induced by irradiation was measured by nanoindentation. Ni/Si/Mn clusters were identified in all conditions except the one irradiated around 600 °C to 3.23 dpa. The compositions of Ni/Si/Mn clusters were found to be converging to G phase stoichiometrically with increasing dose, with Mn partially substituted by Cu. Significant coarsening of this phase was observed in high temperature cases, with total dissolution of intragranular G phase after prolonged irradiation. A similar trend was also identified for dislocation loops. The results obtained in this experiment provide evidences that the absence of dislocation loops in some specimens irradiated to high dose level under high irradiation temperature range (typically above 500 °C) is not due to the suppression of nucleation and growth by high point defect recombination rate, but rather fast coalescence of dislocation loops. Hardness measurements show different dose dependences for two temperature ranges. For specimen irradiated around 600 °C significant hardening before 0.5 dpa followed by softening process was observed, while in lower temperature range (450 °C ~ 500 °C) the normal hardening pattern with increasing dose was observed.
AB - A Fe-9Cr ferritic martensitic (F/M) steel T91 was neutron-irradiated in the Advanced Test Reactor up to 3.96 dpa in two temperature ranges, 466 °C to 534 °C and 571 °C to 632 °C. The microstructure evolution including dislocation loops, precipitation, segregation of elements and phase stability were studied using analytical scanning-transmission electron microscopy and atom probe tomography. The hardening induced by irradiation was measured by nanoindentation. Ni/Si/Mn clusters were identified in all conditions except the one irradiated around 600 °C to 3.23 dpa. The compositions of Ni/Si/Mn clusters were found to be converging to G phase stoichiometrically with increasing dose, with Mn partially substituted by Cu. Significant coarsening of this phase was observed in high temperature cases, with total dissolution of intragranular G phase after prolonged irradiation. A similar trend was also identified for dislocation loops. The results obtained in this experiment provide evidences that the absence of dislocation loops in some specimens irradiated to high dose level under high irradiation temperature range (typically above 500 °C) is not due to the suppression of nucleation and growth by high point defect recombination rate, but rather fast coalescence of dislocation loops. Hardness measurements show different dose dependences for two temperature ranges. For specimen irradiated around 600 °C significant hardening before 0.5 dpa followed by softening process was observed, while in lower temperature range (450 °C ~ 500 °C) the normal hardening pattern with increasing dose was observed.
KW - Dislocation loop
KW - Ferritic/Martensitic (F/M) steel
KW - G phase
KW - Irradiation hardening
KW - Neutron irradiation
UR - https://www.scopus.com/pages/publications/85111986927
UR - https://www.mendeley.com/catalogue/b66bce30-dbd0-3f82-a3ad-c0f08ccec337/
U2 - 10.1016/j.jnucmat.2021.153207
DO - 10.1016/j.jnucmat.2021.153207
M3 - Article
AN - SCOPUS:85111986927
SN - 0022-3115
VL - 557
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
M1 - 153207
ER -