ABSTRACT
Acknowledgments ................................................................................................ 601
References ............................................................................................................ 601
15.1 INTRODUCTION
Investigators have used a wide variety of methods to characterize local electrochem-
ical processes such as those that might develop at intermetallics, second phase
particles, grain boundaries, and other surface heterogeneities. As far back as the
1940s, Dix and Brown (1-3) used a masking technique to measure the potential of
second-phase constituents and grain boundaries in Al-Cu (4% Cu) and Al-Mg
alloys. Using a Bakelite varnish as a mask, samples were produced that exposed
only the precipitate, grain boundary area, or grain centers to solution. While there
have been many techniques over the years that allow analysis of the anode and
cathode separately and have provided valuable insight into local electrochemical
processes (the Dix and Brown mechanism for SCC in Al alloys survives even today),
a method for measuring the local potential and current distributions for a freely
corroding surface containing both anodic and cathodic processes is highly desirable.
