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.