Small angle X-ray scattering of helium bubbles in nickel

Singlecrystalline and polycrystalline nickel foils were homogeneously helium implanted with high energy α-particles at room temperature (RT) and at 723 K (HT) with nominal helium concentrations from 2000 appm up to 8000 appm and subsequently annealed at temperatures up to 1073 K. From intermediate small angle X-ray scattering (SAXS) measurements helium bubble radii and bubble densities were extracted. While in the HT implanted samples the bubble sizes grow very slowly in the RT implanted polycrystals a bi-modal size distribution develops for temperatures >900 K in contrast to the singlecrystalline sample. In this sample the helium gas pressure within the helium bubbles were determined to 12 GPa, which is 4.5 times the equilibrium pressure, by the anisotropy of the forward scattering intensity