Corrosion behavior of AlZnMgCu/TiB₂ composites prepared via the in-situ generation of TiB₂

AlZnMgCu/TiB₂ composites are prepared via the in-situ generation of TiB₂ ceramic particles and subjected to hot extrusion and heat-treatment. XRD, SEM, EDS and TEM are used to characterize the composition, lattice structure and distribution of the secondary phases. The corrosion behavior of the composites is studied by electrochemical impedance spectroscopy, potential polarization measurements and corrosion morphology analysis. The effects of MgZn₂ and Al₂Cu precipitated phases and TiB₂ ceramic particles on the corrosion behavior are discussed. The results show that the TiB₂ ceramic particles are distributed along the extrusion direction and grain boundaries. Nano-sized MgZn₂ and Al₂Cu precipitates are evenly distributed in the α-Al matrix and form large grain boundary precipitates, resulting in precipitation-free zones. The corrosion of the composites is mainly pitting and intergranular corrosion. The pitting corrosion occurs in the α-Al matrix around TiB₂ ceramic particles and the θ phase. Two-electrode coupling systems are formed in the presence of TiB₂ ceramic particles, which explain the mechanism behind the reduced corrosion of the α-Al matrix.