Exploring the morphologies and corrosion performances of AZ31 alloy composites reinforced with silicon nitride

Abstract

In this study, the effects of silicon nitride (Si3N4) particles on the microstructure and corrosion characteristics of AZ31 matrix composites in a 3.5% NaCl solution are examined with the help of an electrochemical test. Varying wt.% of Si3N4 particles (2, 4, 6, 8, 10, and 12 %) is used to fabricate matrix composites via a vacuum-assisted stir-casting approach. The developed composites and base alloys are characterized by energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM). Microscopic images demonstrate that the addition of reinforcement enhances the microstructural interfacial integrity between the Si3N4 and AZ31 matrix. EDAX results confirm the presence of Si3N4 particles in composites. The findings of electrochemical studies confirmed that AZ31's corrosion resistance substantially improved as its Si3N4 content increased. AZ31-10%Si3N4 exhibits a more tremendous corrosion potential (Ecorr) and a two-order-of-magnitude lower corrosion current density (icorr). Compared to the other samples, AZ31-10%Si3N4 exhibits superior polarization resistance. Compared to AZ31-2%Si3N4, AZ31-10%Si3N4 exhibits a 3.5-fold increase in polarization resistance. The results show that the AZ31 alloy with 10% Si3N4 exhibits superior corrosion resistance, followed by the AZ31-12%Si3N4, AZ31-8%Si3N4, AZ31-6%Si3N4, AZ31-4%Si3N4, and AZ31-2%Si3N4. The collective outcomes of the investigation indicate that the AZ31-10%Si3N4 composite may have the potential to enhance the corrosion behavior of AZ31 alloys.

Keywords

• AZ31 alloy
• AZ31/Si3N4 composites
• Potentiodynamic polarization
• Electrochemical impedance spectroscopy
• Tafel plot
• Nyquist plot