ENHANCED CORROSION RESISTANCE AND MECHANICAL INTEGRITY OF AL6061/BERYL METAL COMPOSITES: AN ELECTROCHEMICAL STUDY IN ACIDIC CHLORIDE AND ALKALINE MEDIA

Al6061 aluminium alloy has been widely used in aerospace, automotive, and marine industries for its low density, excellent mechanical properties, and medium corrosion resistance. Nevertheless, its structural reliability is still limited by the susceptibility to localised corrosion in severe environments. In the present investigation, beryl (Be3Al2Si6O18), a natural beryllium aluminium cyclosilicate, is utilised as a reinforcement phase to enhance corrosion resistance and mechanical properties of Al6061 alloy. In order to make the aluminium/boron balide MMCs more homogeneous and have better interface bonding, these stir-cast MMCs with 2, 4 and 6 wt% of beryl were successfully extruded. The mechanical properties, such as hardness, density and porosity, were initially determined, then the corrosion behaviour was explored electrochemically in 0.5 M HCl and 0.1 M NaOH solutions by means of Tafel extrapolation and EIS methods. The microstructure and phase characteristics were systematically investigated using a scanning electron microscope (SEM) and an X-ray diffractometer (XRD). Results showed that the composite with 6 wt% beryl had the smallest current density and maximum LIN, described by a higher resistance to polarisation, which proved an improved stability of the passive film. These results indicate that the incorporation of beryl reinforcement via CEP effectively enhances not only the corrosion resistance but also the structural property of Al6061 alloy, and thus its potential for use in corrosive, aggressive, and high-simultaneous property engineering conditions.