KI crystals were irradiated with deuterons or alpha particles of 14 MeV per nucleon to doses between 2-6 × 1018 m-2, and subsequently are annealed at 393 K. Surface replicas reveal a colloid inclusion distribution as a function of ion penetration depth, with a strong maximum near the stopping zone. These K inclusions are directly revealed by T.E.M., with an f.c.c. structure ; these arise from thermal aggregation of F centres created by ionisation and nucleate preferentially in the stopping zone. Certain contrast features suggest a possible hybride formation with deuterium-implanted crystals, and spherical inclusions which could be helium bubbles with α-irradiated ones