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Detection of nanoscale η‐MgZn 2 phase dissolution from an Al‐Zn‐Mg‐Cu alloy by electrochemical microtransients
Author(s) -
Wloka Joachim,
Virtanen Sannakaisa
Publication year - 2008
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.2868
Subject(s) - dissolution , alloy , intermetallic , materials science , grain boundary , nanoscopic scale , transmission electron microscopy , grain size , polarization (electrochemistry) , phase (matter) , electrochemistry , analytical chemistry (journal) , metallurgy , microstructure , nanotechnology , chemical engineering , chemistry , electrode , organic chemistry , chromatography , engineering
In this article we demonstrate how the dissolution of nanosize intermetallic particles present in Al alloys can be detected using microelectrochemical techniques. The local electrochemical properties of a high‐strength Al‐Zn‐Mg‐Cu alloy, which contains nanoscale η‐MgZn 2 phases, were investigated with a microcapillary cell. At the open‐circuit potential (OCP) with the sample surface in the range of 1000 µm 2 , potential fluctuations (microtransients) can be observed. Under polarization of such small areas, current transients are detected in the passive range of the alloy. An estimation of the size of dissolution events from the charge passed during the current transient leads to the conclusion that the current transients could stem from the dissolution of η‐phase particles, with diameters in the order of 100 nm. This size scale corresponds well with the size of the grain‐boundary MgZn 2 . Transmission electron microscopy (TEM) and high‐resolution SEM images provide further insights for possible mechanisms leading either to potential or to current microtransients. Copyright © 2008 John Wiley & Sons, Ltd.