CORROSION BEHAVIOR OF SOME VAPOR-DEPOSITED MAGNESIUM ALLOYS

Binary magnesium alloys containing chromium, manganese, or titanium we re made using a physical vapour deposition technique. The corrosion re sistance of the alloys was assessed in aqueous chloride solutions usin g total immersion tests in quiescent 600 mmol L(-1) NaCl solutions. Al loying with manganese or titanium was found to lower the corrosion rat e of magnesium over most of the compositional ranges of interest, wher eas addition of chromium had a detrimental effect on the corrosion res istance of magnesium. The lowest corrosion rate was recorded for a Mg- Ti alloy where the value obtained was about 80 times lower than that f ound for vapour deposited pure magnesium. Open circuit corrosion poten tial measurements conducted in 600 mmol L(-1) NaCl solution showed tha t additions of chromium, titanium, and manganese also produced deposit s which were significantly more noble than pure magnesium, suggesting that these alloys would be less susceptible to galvanic corrosion. (C) Crown Copyright 1995/DERA.