The use of microcapillary techniques to study the corrosion resistance of AZ91 magnesium alloy at the microscale

The AZ91 alloy is composed of Mg-17(Al, Zn)(12) precipitates, an eutectic phase around these precipitates, AlMn intermetallic particles and an alpha-Mg solid solution (matrix). The corrosion behaviour of AZ91 was investigated at the microscale by means of the electrochemical microcell technique, which uses extremely small capillaries (diameters between 5 and 10 mu m). Experiments were conducted in 0.1 M NaClO4 at 25 degrees C. The beta-Mg-17(Al, Zn)(12) precipitates were found to have the highest corrosion resistance, whereas the eutectic phase was very active (pitting potential of approximately -1400 mV vs. Ag/AgCl). The alpha-Mg solid solution displayed better corrosion resistance than the eutectic phase. (C) 2011 Elsevier Ltd. All rights reserved.