Electrochemical behaviour of TiO2 reinforced Al 7075 composite

Microstructures of sintered Al 7075 alloy and Al 7075 alloy reinforced with varying TiO2 composites exhibited uniform distribution of TiO2 particles, but clustering and porosity have increased with TiO2 content. TEM micrographs of the Al 7075 alloy and Al 7075 + TiO2 composite of peak aged T6 (PA) temper showed some coarse and numerous very fine η′ (MgZn2) precipitates, and equilibrium η (MgZn2) precipitates along the grain boundaries. Potentiodynamic electrochemical polarisation studies on the Al 7075 alloy of different tempers and Al 7075 + TiO2 composites in 3.5 wt.% NaCl solution showed that the corrosion potentials (Ecorr) have shifted towards noble direction with the addition of TiO2, and there is an increase of corrosion current density (icorr) beyond 10 vol.% TiO2 in the composites. This is attributed to the increase in particle-matrix interface areas enhancing pitting corrosion. Optical micrographs of the corroded surface of 30% TiO2 composites exhibited maximum pitting damage.