<p>The micro-structure, residual stresses, and micro-distortions generated near the surface in the AA6061-B₄C metal matrix composite by glass-bead blasting are investigated and compared with those of the bulk. In contrast to the bulk, the sublayer is under compression and contains an extremely low density of B₄C and a high density of dislocations. Corrosion behaviour was studied in H₃BO₃ after immersion at the OCP and after accelerated tests. In the sublayer, initial rapid oxidation (formation of a homogeneous oxide film) is followed by slow oxidation (average corrosion rate: 2 µm/year); the oxidation front moves parallel to the surface. In the bulk, oxidation takes place along preferential paths defined by the distribution of B₄C. The driving force is the galvanic coupling between B₄C and the matrix. Once corrosion proceeds, corrosion products (oxidation of the sublayer) become weakly adherent, peeling off locally. The bulk is then directly exposed to the solution, promoting corrosion.</p>