Corrosion behaviour of powder metallurgy aluminium matrix composite reinforced with alumina Saffil™ short fibre

Abstract

The corrosion behaviour of PM Al composite will be affected by the presence of alloying element and reinforcing phase in the composite. This study focused on magnesium and alumina Saffil™ short fibres reinforcement affected to corrosion behaviour of PM AMCs in 3.5wt% NaCl. PM Al composite and PM Al-Mg composite were fabricated from flaky aluminium powder, 2wt% granular magnesium and 15wt% alumina Saffil™ short fibres. The corrosion testing was done using potentiostat Gamry G300 to create Tafel plot and polarization curve. The corrosion effects were analyse using scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). From experiment, pitting was localized surrounding the magnesium constituents which occur randomly throughout the surface of PM Al-Mg composite. XRD analysis revealed that aluminum oxide (δ-Al Al1.67O4), aluminium hydroxide (Al (OH)3) and aluminium oxide (α-Al2O3) phases were detected in oxide film. The corrosion current density (Icrit) of PM Al composite is lower than PM Al-Mg composite which is 2.0 x 10-1 A/cm2 and 4.0 x10-1 A/cm2, respectively. Magnesium is used as inhibitor in corrosion behaviour of PM Al-Mg composite have been changed and protected with a stable formation of oxide film. The corrosion resistance of PM Al-composite was decreased with the presence of alumina Saffil™ short fibres in composite due to discontinuities in oxide film provided the corrosion initiated in sample.