Material performance in extreme radiation environments is central to the design of future nuclear reactors. Radiation induces significant damage in the form of dislocation loops and voids in irradiated materials, and continuous radiation often leads to void growth and subsequent void swelling in metals with low stacking fault energy. Here we show that by using in situ heavy ion irradiation in a transmission electron microscope, pre-introduced nanovoids in nanotwinned Cu efficiently absorb radiation-induced defects accompanied by gradual elimination of nanovoids, enhancing radiation tolerance of Cu. In situ studies and atomistic simulations reveal that such remarkable self-healing capability stems from high density of coherent and incoherent twin boundaries that rapidly capture and transport point defects and dislocation loops to nanovoids, which act as storage bins for interstitial loops. This study describes a counterintuitive yet significant concept: deliberate introduction of nanovoids in conjunction with nanotwins enables unprecedented damage tolerance in metallic materials.
Bibliographical noteFunding Information:
Y.C. and X.Z. acknowledge financial support primarily by NSF-DMR-Metallic Materials and Nanostructures Program under grant no. 1304101 (in situ radiation and microscopy). Y.L. who works on fabrication of nanotwinned metals is supported by DOE-OBES under grant no. DE-SC0010482. S.S. and J.W. acknowledge the support provided by the Los Alamos National Laboratory Directed Research and Development (LDRD-ER20140450) and J.W. also acknowledges the Start-up provided by the University of Nebraska-Lincoln. We also thank Peter M. Baldo and Edward A. Ryan at Argonne National Laboratory and L. Jiao in Texas A&M University for their help during in situ irradiation experiments. The IVEM facility at Argonne National Laboratory is supported by DOE-Office of Nuclear Energy. Access to the DOE—Center for Integrated Nanotechnologies (CINT) at Los Alamos and Sandia National Laboratories and Microscopy and Imaging Center at Texas A&M University is also acknowledged. The open access publishing fees for this article have been covered by the Texas A&M University Online Access to Knowledge (OAK) Fund, supported by the University Libraries and the Office of the Vice President for Research.
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