Unmasking the influence of TiC on passivation and pitting initiation of aluminum matrix composites

The effect of TiC on corrosion process, particularly the passive and initial stages, is unclear. The passivation and initial corrosion of 2024-TiC AMCs are investigated in this report. It is found that a small amount of TiC improves corrosion resistance by reducing galvanic corrosion current density and forming a stable passive layer with low Cl⁻ adsorption and cation vacancy density, minimizing dissolution. However, excessive TiC causes uneven distribution, aggregation of Cl⁻, and passive film rupture, leading to anode aluminum dissolution and accelerated pitting corrosion propagation. These findings highlight the balance requirement for optimal TiC additive used in enhancing corrosion resistance.