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Download fileRadiation-Induced Helium Nanobubbles Enhance Ductility in Submicron-Sized Single-Crystalline Copper
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posted on 2016-06-01, 00:00 authored by Ming-Shuai Ding, Jun-Ping Du, Liang Wan, Shigenobu Ogata, Lin Tian, Evan Ma, Wei-Zhong Han, Ju Li, Zhi-Wei ShanThe
workability and ductility of metals usually degrade with exposure
to irradiation, hence the phrase “radiation damage”.
Here, we found that helium (He) radiation can actually enhance the
room-temperature deformability of submicron-sized copper. In particular,
Cu single crystals with diameter of 100–300 nm and containing
numerous pressurized sub-10 nm He bubbles become stronger, more stable
in plastic flow and ductile in tension, compared to fully dense samples
of the same dimensions that tend to display plastic instability (strain
bursts). The sub-10 nm He bubbles are seen to be dislocation sources
as well as shearable obstacles, which promote dislocation storage
and reduce dislocation mean free path, thus contributing to more homogeneous
and stable plasticity. Failure happens abruptly only after significant
bubble coalescence. The current findings can be explained in light
of Weibull statistics of failure and the beneficial effects of bubbles
on plasticity. These results shed light on plasticity and damage developments
in metals and could open new avenues for making mechanically robust
nano- and microstructures by ion beam processing and He bubble engineering.