Influence of heat treatment and microstructure on the corrosion of magnesium alloy Mg-10Gd-3Y-0.4Zr

Journal of Applied Electrochemistry (Impact Factor: 2.15). 06/2008; 39(6):913-920. DOI: 10.1007/s10800-008-9739-4

ABSTRACT The corrosion of Mg alloy Mg-10Gd-3Y-0.4Zr, in the as-cast (F), solution treated (T4) and aged (T6) conditions, was investigated
in 5% NaCl solution by immersion tests and potentiodynamic polarization measurements. The as-cast (F) condition had the highest
corrosion rate due to micro-galvanic corrosion of the α-Mg matrix by the eutectic. Solution treatment led to the lowest corrosion
rate, attributed to the absence of any second phase and a relatively compact protective surface film. Ageing at 250°C increased
the corrosion rate with increasing ageing time to 193h attributed to increasing micro-galvanic corrosion acceleration of
the Mg matrix by increasing amounts of the precipitates. Ageing for longer periods caused a decrease in the corrosion rate
attributed to some barrier effect by a nearly continuous second-phase network. Electrochemical measurements did not give accurate
evaluation of the corrosion rate in agreement with the immersion tests.

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