The role of interface structure on the trapping of He in Cu-Nb nanocomposites was investigated by comparing He bubble formation in nano-multilayers grown by PVD, nanolaminates fabricated by accumulative roll bonding (ARB), and 3D nanocomposites obtained by high pressure torsion (HPT). All samples were implanted with 1 MeV He ions at room temperature and characterized by cross section transmission electron microscopy (TEM). The critical He concentration leading to bubble formation was determined by correlating the He bubble depth distribution detected by TEM with the implanted He depth profile obtained by SRIM. The critical He dose per unit interfacial area for bubble formation was largest for the PVD multilayers, lower by a factor of ∼1.4 in the HPT nanocomposites annealed at 500 °C, and lower by a factor of ∼4.6 in the ARB nanolaminates relative to the PVD multilayers. The results indicate that the (111)FCC||(110)BCC Kurdjumov-Sachs (KS) interfaces predominant in PVD and annealed HPT samples provide more effective traps than the (112)KS interfaces predominant in ARB nanolaminates; however, the good trapping efficiency and high interface area of 3D HPT structures make them most attractive for applications.
Bibliographical noteFunding Information:
This work was supported in part by the Center for Materials at Irradiation and Mechanical Extremes, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number 2008LANL1026 . The work was carried out in part in the Frederick Seitz Materials Research Laboratory (FS-MRL) Central Research Facilities, University of Illinois. Stimulating discussions with Drs. A. Misra (LANL, University of Michigan) and I. Beyerlein (LANL) are gratefully acknowledged. We also thank D. Jeffers (FS-MRL) for his assistance with operation of the Van de Graaff accelerator used to irradiate our samples and Dr. M. Sardela (FS-MRL) for his assistance with XRD characterization and texture measurements.
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- He bubbles
- Radiation effects