Abstract
The effect of rapid solidification on the corrosion behaviour in aerated 0.001 M NaCl solution of Mg-Al alloys containing 9.6 to 23.4wt% AI has been investigated in comparison with chill-cast material. Polarization studies show that rapid solidification decreases corrosion current by up to two orders of magnitude corresponding to a corrosion rate of 6 to 11 mil y−1. Increasing the aluminium content in solid solution by rapid solidification gave rise to a steep increase in pitting potential between 10 and 23 wt% Al and resulted in development of an anodic plateau at ∼ 30μAcm−2 attributable to magnesium depletion for the alloy surface and formation of a protective film. Chemical analysis of the electrolyte as a function of dissolution time for the rapidly solidified material indicated that initially only magnesium dissolved and that this dissolution of magnesium ceased within 2 to 5 min. The results indicate the formation of an aluminium-enriched interdiffusion zone at the surface underlying a more stable surface oxide than for ingot-processed Mg-Al-based alloys.
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Hermann, F., Sommer, F., Jones, H. et al. Corrosion inhibition in magnesium-aluminium-based alloys induced by rapid solidification processing. J Mater Sci 24, 2369–2379 (1989). https://doi.org/10.1007/BF01174498
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DOI: https://doi.org/10.1007/BF01174498