Focused-ion-beam machined compression specimens were used to investigate the effect of nanometer-scale helium bubbles on the strength and deformability of sputter-deposited Cu and Cu/Nb multilayers with different layer thickness. The flow strength of Cu films increased by more than a factor of 2 due to helium bubbles but in multilayers, the magnitude of radiation hardening decreased with decreasing layer thickness. When the layer thickness decreases to 2.5 nm, insignificant hardening and no measurable loss in deformability is observed after implantation.
Bibliographical noteFunding Information:
This work is sponsored by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Energy Frontier Research Center (EFRC) under Award No. 2008LANL1026 . The helium ion implantation work is supported, in part, by LANL-LDRD. Nanoindentation was performed, through an approved user project, at the Center for Integrated Nanotechnologies (CINT), a DOE-BES sponsored national user facility. The authors thank J.P. Hirth, W.D. Nix, R.G. Hoagland, G.R. Odette and M.J. Demkowicz for valuable discussions, and J.K. Baldwin for sputter deposition.
- Helium bubbles
- Pillar compression
- Radiation-induced strengthening