Improvement in irradiation resistance of FeCu alloy by pre-deformation through introduction of dense point defect sinks
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Improvement in irradiation resistance of FeCu alloy by predeformation through introduction of dense point defect sinks Hao Wu, Qiu-Lin Li*
, Ben Xu, Hai-Long Liu, Guo-Gang Shu, Wei Liu
Received: 16 January 2020 / Revised: 21 April 2020 / Accepted: 10 July 2020 Ó The Nonferrous Metals Society of China and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The irradiation resistance of pre-deformed FeCu alloy was studied using a 3 MeV Fe ion irradiation experiment at room temperature in comparison with that of the as-received sample. Nanoindentation and atom probe tomography (APT) were used to characterize the mechanical properties and solute distribution. The stress–strain curve obtained by nanoindentation shows that the yield strength (r0.2) of the pre-deformed sample is unexpectedly reduced with an increase in the irradiation dose to five displacements per atom (dpa). We suggest that it results both from the decrease in the dislocation density and the suppression of defects during irradiation. APT shows that the nucleation of the Cu cluster is suppressed; however, its growth is promoted in the pre-deformed sample, resulting in the formation of sparse and coarse clusters at 1 dpa irradiation. These coarse Cu clusters were then unexpectedly refined to finer grains with an increase in the irradiation dose to 5 dpa. Theoretically, the improvement in the resistance to irradiation in the pre-deformed sample is attributed to the dense point-defect sinks, that is, the dislocations and grain boundaries introduced by pre-deformation. In addition, the contributions of the dislocations and grain boundaries to the sink strength are estimated for H. Wu, Q.-L. Li* Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China e-mail: [email protected] H. Wu, B. Xu, H.-L. Liu, W. Liu School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China G.-G. Shu State Key Laboratory of Nuclear Power Safety Monitoring Technology and Equipment, China Nuclear Power Engineering Co. Ltd, Shenzhen 518172, China
both the as-received and pre-deformed samples. The results indicate that dislocations, rather than grain boundaries, play a major role after deformation. Keywords Reactor pressure vessel; Irradiation damage; Pre-deformation; Dislocation density; Cu-rich clusters
1 Introduction Nuclear energy is green and economical; however, the operational safety of nuclear power plants has always been a major concern, limiting its development. To prevent nuclear leakage, some barriers are designed in the reactor, among which the reactor pressure vessel (RPV) is the last and most important barrier to block neutron irradiation. However, it is almost impossible to replace a failed RPV because of its large size; thus, the service life of a nuclear reactor depends on that of its RPV. In light water reactors, RPV is serviced at a temperature of * 290 °C, at a pressure of * 7 MPa in a boiling water reactor (BWR) and * 14 MPa in pressurized water reactors (PWRs) [1]
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