Damage and Diffusion in Aluminum and an Al-Al₂O₃ Alloy Following Bombardments with Oxygen or Inert Gas

Abstract

Damage and diffusion phenomena in aluminum and an Al-Al₂O₃ alloy (SAP) have been studied following bombardments with oxygen or inert gas. Use is made of transmission electron microscopy, measurements of gas release, and depth-distribution measurements. A dose and dose-rate dependence for the appearance of damage in aluminum and SAP is found for both oxygen and neon bombardments at 9 keV. The damage is more aligned, however, when oxygen is used than when neon is used. The difference in arrangement can be explained by assuming a different mobility of the loops depending on whether oxygen or neon is present in the aluminum lattice. The annealing behavior of the damage also depends on which gas is used in the bombardment. In the case of oxygen, the damage anneals out roughly in the temperature range for aluminum self-diffusion (150–200°C). In the case of neon, large loops and tangles are present even at 500°C. Moreover, neon-bombarded specimens at high temperatures show small bubbles and large undefined features. The latter are assumed to be gas pockets or blisters near the metal-oxide-skin interface. Gas-release experiments following krypton and xenon bombardments at > 5 keV show that more than 99% of the gas is retained to the melting point This is explained by means of depth distributions to be due to trapping near the metal-oxide-skin interface and, thus, confirms the observation of gas pockets or blisters. After bombardments below ~ 5 keV, gas is released beginning at the ambient temperature. Such release is analogous to that observed in other systems at low bombardment energies.