He implantation of bulk Cu-Nb nanocomposites fabricated by accumulated roll bonding

We perform room temperature and elevated temperature He implantation of bulk Cu-Nb nanocomposites synthesized by accumulated roll bonding (ARB). Transmission electron microscopy (TEM) reveals that nanoscale He precipitates form preferentially along Cu-Nb interfaces during implantation at 20 °C and 450°C. Bubble-free zones may be identified near interfaces after implantation at 450°C. He implantation at 480°C results in large, faceted cavities in thick Cu layers and highly elongated cavities in thin Cu layers. Only nanoscale bubbles are seen in Nb layers after implantation at 480°C. Similar to vapor deposited Cu-Nb multilayers, ARB Cu-Nb nanocomposites exhibit He precipitate morphologies that are highly sensitive to implantation temperature and layer thickness.