A bilayer system composed of an Al 610 Å film evaporated onto a KCl single crystal and a pure KCl single crystal were both implanted with 300 keV209Bi+. The Bi depth distribution agrees with the Monte-Carlo simulation predictions in both systems. Diffusion of Bi in the Al film and in the KCl substrate of the Al/KCl system, as well as in the pure KCl crystal, is studied as a function of isochronal annealing. For low temperatures up to 200°C we observe enhanced diffusion of Bi in all systems. At higher temperatures (up to 500°C) a regular diffusion governs the depth profiles.