Microstructural and electrochemical behavior of spark plasma sintered (Cu-10Zn) + Al2O3 nanocomposites

Abstract

The present work deals with developing Al2O3 reinforced α-brass (Cu-10Zn) nanocomposites through spark plasma sintering and evaluated its electrochemical properties in a 3.5% NaCl aqueous solution. Microstructural analysis revealed the uniform dispersion of Al2O3 particles with inter-particle spacing ∼2.45 µm in 3 wt.% Al2O3 nanocomposites. The initiation of Al2O3 clustering and vast clustering of particles with wide particles-free-zone were observed in 6 and 9 wt.% Al2O3 nanocomposites. X-ray diffraction peaks confirm the crystallinity and incorporation of Al2O3 in the α-brass matrix. The corrosion behavior was studied by measuring the change in open-circuit potential values, electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and potentiodynamic polarization (PDP) studies in 3.5% NaCl solution. The 3 wt.% Al2O3 nanocomposites exhibited lower icorr value than the Cu-10Zn matrix and other Al2O3 reinforced nanocomposites. The EIS results confirm the surface layer enhancement and resistance to charge transfer in 3 wt.% Al2O3 nanocomposites due to their uniform distribution in the matrix. The uniformly embedded reinforcement particles abridged the prospects of galvanic coupling, which resulted in the upliftment of corrosion resistance and passivation behavior. An increase in the icorr value beyond 3 wt.% Al2O3 nanocomposites was due to the clustering of reinforced nanoparticles and vast particle-free zones and caused intergranular corrosion.