Attempts have been made to estimate corrosion rate and electrochemical parameters of aluminum in 5 mass% phosphoric acid solution which is in open-to-air and stagnant solution condition in the view point of corrosion weight loss and polarization measurements. It is shown that the dissolution of aluminum in phosphoric acid solution behaves in the fast manner and like a general dissolution manner. The corrosion rate and transfer coefficient of rate-determining step for hydrogen ion reduction reaction are estimated about 0.04 mA cm^-2 from the corrosion weight loss and 0.5, respectively. And the current density calculated by polarization resistance method is 0.03 mA cm^-2 which roughly coincided with the corrosion rate of 0.04 mA cm^-2 estimated above.

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Recrystallization behaviors in 3004 aluminum alloy was observed on the same view field in a specimen with SEM (Scanning Electron Microscope) -EBSD (Electron Back Scatter Diffraction) system. Specimen were heat-treated at 873 K for 20 h and then its surface was observed by SEM-EBSD. The specimen was cold-rolled at a reduction rate of 30% and electoropolished. After that annealed at 673 K. Intermittent annealing, Ar ion-polishing and EBSD measurement were repeated. Particle Stimulated Nucleation (PSN) and Strain induced grain boundary migration (SIBM) were observed when the specimen after cold-rolling was annealed. More often than not, recrystallized grains were formed by PSN. PSN, however, was not always observed nearby coarse precipitate. PSN mechanism was not occurred by nucleation but by growth of dislocation cell nearby precipitate. Its orientation did not change when the dislocation cell grew to recrystallized grain. Although orientation of dislocation cell surrounded high angle boundary was different from one of surrounded subgrains, its dislocation cell did not grow into recrystallized grain. Growth of grain would be affected by stored energy of surrounded grains.

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