Bubbles formation in helium ion irradiated Cu/W multilayer nanocomposites: Effects on structure and mechanical properties

Abstract

This study investigates the effects of He bubbles on structural and mechanical properties of sputter-deposited Cu/W multilayers. A multilayer with a periodicity of 10 nm was deposited and subjected to helium ion irradiation with two different fluences. He bubbles formed mostly in Cu layers and their distribution was affected by He concentration and radiation damage. According to SRIM calculations, in low He concentration regions bubbles formed mostly along interfaces, while more homogeneously distributed bubbles were found in Cu layers and along columnar grain boundaries in higher He concentration regions. We suggest that the capability of interfaces to annihilate point defects is weakened by the He bubbles shielding effect. Nanoindentation tests revealed a hardness decrease amounting to ~ 0.5 and ~ 1 GPa for low and high fluences, respectively. The observed softening effect is attributed to He storage-induced changes in residual stresses and columnar grain boundary/interfacial sliding facilitated by He bubbles.

Bubble formation in nuclear glasses: A review

“…Comparing the results of these studies is not straightforward. Evidence from ion irradiation of metals has shown that dose rate (flux) governs bubble formation 47,48 however, few studies have provided this information, or the information required to calculate it. Nevertheless, some conclusions can be drawn.…”

Recent progress of radiation response in nanostructured tungsten for nuclear application

“…On the other hand, He bubbles aligned along the interface were observed in thick period W/Cu. The formation of bubbles was mostly found in Cu layers and along columnar GBs [87], which might result from individual He atom that was allowed to migrate through interfaces or surrounding layers [88]. Dong et al [75] systematically studied the responses of W/Cu multilayered nanofilms irradiated by 40 keV He + , 6.4 MeV Xr 23+ and 200 MeV Xr 14+ ions, which simulated He bubble damage, neutron irradiation and fission fragment damage, respectively.…”

Imaging the in-plane distribution of helium precipitates at a Cu/V interface

“…They have been especially fruitful for investigations of the nucleation, growth, and interaction of helium (He) precipitates at fcc/bcc interfaces [4][5][6][7]. To date, however, experimental imaging of He precipitates at these interfaces has been confined to viewing the interfaces edge-on [4][5][6][7].…”