600‐keV Bi was implanted into an Al/Ti bilayer structure. There is good agreement between the Bi depth profile measured by Rutherford backscattering and corresponding theoretical prediction (Monte Carlo codetrim). After annealing at low temperatures, the pronounced structure of Bi concentration at the Al/Ti interface vanishes, and the buildup of a surface precipitation is observed. At 500 °C annealing, strong Bi diffusion sets in, associated with the intermixing of the substrate components. A thin oxide layer present at the surface acts as a diffusion barrier for Bi, resulting in Bi segregation at the oxide/alloy interface.