The research comes out of the Texas A&M University, from a May 29, 2015 news item on Azonano,
Material performance in extreme radiation environments is central to the design of future nuclear reactors. Radiation in metallic materials typically induces significant damage in the form of dislocation loops and continuous void growth, manifested as void swelling. In certain metallic materials with low-to-intermediate stacking fault energy, such as Cu [copper] and austenitic stainless steels, void swelling can be significant and lead to substantial degradation of mechanical properties.
By using in situ heavy ion irradiation in a transmission electron microscope (in collaboration with M.A. Kirk at IVEM facility at Argonne National Lab), Zhang’s [Xinghang Zhang] student, Dr. Youxing Chen, reported a surprising phenomena: during radiation of nanotwinned Cu, preexisting nanovoids disappeared.
A May 28, 2015 Texas A & M University news release, which originated the news item, expands on the theme,
The self-healing capability of Cu arises from the existence of three-dimensional coherent and incoherent twin boundary networks. Such a network enables capture and rapid transportation of radiation induced point defects and their clusters to nanovoids (as evidenced by in situ radiation experiments and molecular dynamics simulations performed in collaboration with Jian Wang at Los Alamos National Laboratory), and thus lead to the mutual elimination of defect clusters and nanovoids.
This study also introduces the concept that deliberate introduction of nanovoids in conjunction with nanotwins may enable unprecedented radiation tolerance in metallic materials. [emphasis mine] The mobile twin boundaries are swift carriers that load and transfer “customers” (defect clusters), and nanovoids are also necessary to accommodate these “customers.” The in situ radiation study also shows that after annihilation of nanovoids, the self-healing capability of nanotwinned Cu is degraded, highlighting the significance of nanovoids. The concept developed from this study, the combination of nanovoids with nanotwin networks, may also stimulate the design of damage tolerant materials in general that are subjected other extreme environments, such as high stress and high pressure impact.
Here’s a link to and a citation for the paper,
Damage-tolerant nanotwinned metals with nanovoids under radiation environments by Y. Chen, K Y. Yu, Y. Liu, S. Shao, H. Wang, M. A. Kirk, J. Wang, & X. Zhang. Nature Communications 6, Article number: 7036 doi:10.1038/ncomms8036 Published 24 April 2015
This paper is open access.