The electrochemical characteristics of an ultra–fine grain γ/-Ni3Al coating in 3.5% NaCl solution

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Author(s) Onyeachu B.I | Oguzie E.E | Njoku D.I | Ukaga I
Pages 728-735
Volume 3
Issue 11
Date November, 2014
Keywords Grain refinement, γ/–Ni3Al, EIS, Al2O3, corrosion resistance
Abstract

The study of the electrochemical characteristics of an ultrafine–grain γ/–Ni3Al coating was undertaken, after exposure for 72 h in 3.5% NaCl solution, using open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The ultrafine–grain γ/–Ni3Al was fabricated by annealing an electrodeposition of a Ni–Al composite coating at 600 oC for 1 h. Compared with an arc–melted γ/–Ni3Al alloy; the ultrafine–grain γ/–Ni3Al exhibited more positive corrosion potential with lower corrosion current density. This was attributed to the highly refined microstructure of the ultrafine–grain γ/–Ni3Al which promoted a lower transient time for the formation an Al2O3– enriched corrosion product layer.

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