The role of constituent phases on corrosion initiation of NiAl bronze in acidic media studied by SEM–EDS, AFM and SKPFM

• NiAl bronze corrosion initiation was studied in HCl solution.
• AFM, SKPFM and SEM have been employed to map relative nobility.
• Volta potential revealed anodic character of κ phases (tens of mV).
• A correlation between SKPFM results and Work function values was obtained.
• SEM and AFM images of initial sites of corroded sample confirmed SKPFM results.

Scanning electron microscopy (SEM), atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM) were used to examine the role of constituent phases of a NiAl bronze in corrosion initiation in HCl solution. Volta potential revealed anodic character of κ phases with tens of mV higher than copper rich α phase as cathodic matrix. A correlation between SKPFM results and Work function values of constituents was obtained. SEM and AFM images revealed that the iron rich κ phases are the most preferential sites for corrosion initiation.

(a) OM micrograph, (b) topography and (c) Volta potential images obtained at same region on as-polished surface of NiAl bronze alloy.Figure optionsDownload as PowerPoint slide