Study of Electrochemical Behaviour of AZ91 Mg-based Composites

In this research study, electrochemical behaviour of AZ91/12Al₂O₃ and AZ91/12Al₂O₃/3TiC composites are investigated using different methods such as linear polarization resistance, electrochemical spectroscopy, noise measurements, and potential dynamic polarization curves. Both composites have been fabricated by using a two-step stir casting process. These composites include alumina (Al₂O₃) and TiC (titanium carbide) as reinforcing particles amalgamated with AZ91 Mg alloy. However, AZ91 Mg alloy depicts 9% of aluminium, 1% of zinc and rest is balance of pure magnesium, AZ91/12Al₂O₃ signifies AZ91 Mg alloy having 12 wt. % of alumina whereas AZ91/12Al₂O₃/3TiC indicates 3 wt. % of titanium carbide and 12 wt.% of Al₂O₃ in AZ91 Mg alloy. The conclusive result of these methods illustrate that AZ91/12Al₂O₃ composite exhibits high corrosion rate as compared to AZ91/3TiC/12Al₂O₃ composite due to high galvanizing effect (in between corrosive surface) of AZ91 Mg alloy and alumina particles. Lastly, the results of the electrochemical impedance of both composites illustrate the diffusion/adsorption type phenomenon.