Influence of Different Aqueous Media on the Corrosion Behavior of B₄C-Modified Lightweight Al-Mg-Si Matrix Composites

In this study, we have investigated the electrochemical corrosion behavior of boron carbide (B₄C) ceramic-reinforced Al-Mg-Si matrix composites in various aqueous environments (NaOH, NaCl, HCl, and H₂SO₄). The samples were produced by the powder metallurgy (P/M) route and the corrosion investigations were conducted by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) methods. The morphology of the as-prepared and corroded samples was examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies. The investigations revealed that the corrosion resistance of Al-Mg-Si composites is highest in NaCl medium due to a less negative corrosion potential, higher charge transfer (R_ct) resistance, and lower double-layer capacitance (C_dl) as compared to other media. The SEM morphology suggests that B₄C ceramics enhance corrosion resistance by forming a protective barrier layer of OH- and Cl- deposits in the composite and unreinforced alloy, respectively.