Speaker
Description
With the emergence of new manufacturing routes, leading to highly heterogeneous microstructures and/or geometrically complex components, there is a need for advanced electrochemical characterization of light metal degradation at the micro- and nanoscale to efficiently predict their durability.
The scanning electrochemical nanocapillary (SEN) technique allows assessing, in the sub-micrometer range, the local surface reactivity and the influence of anodic/cathodic areas on the corrosion mechanisms of high performance industrial materials. One strength of the technique lies in the possibility to simultaneously track the topography and record the electrochemical response of rough, high-aspect ratio surfaces while only the area under the nanocapillary glass tip (< 100 nm) is exposed to the electrolyte. This allows a direct correlation of the measured electrochemical response to specific micro- or nanostructural features. Consequently, the SEN technique is a promising tool to deepen our mechanistic understanding of microscale galvanic coupling and localized corrosion initiation processes in modern light metal alloys.
The SEN technique has already successfully been applied to characterize the local surface reactivity of very active systems. In the case of Mg, local electrochemical measurements of various purity materials with high lateral resolution are critical to determine the presence, nobility and distribution of nanoprecipitates, induced by the trace amount of impurities. The reactivity of these cathodic sites will drastically impact the corrosion rates of the respective Mg. These observations have been validated on a model Mg50-Fe composites produced by HPT.
The technique has been further applied to investigate the passive surface oxide reactivity on modern Al alloys in aggressive environments. By correlating local potential changes to specific microstructural features, we can identify the ones leading to corrosion initiation and surface damage.
| Speaker Country | Switzerland |
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