AQUEOUS CORROSION OF MAGNESIUM ALLOYS

BS>The aqueous corrosion of Mg alloys was investigated at 53 to 150 deg C. Corrosion rates rose rapidly with temperature, reaching about 3 mils per day at 150 deg C for AZ-31 STAMg-2.5 to 3.5 wt.% Al-0.7 to 1.3 wt.% Zn-0.2 wt.% Mn!. Additions of small amounts of Cu and/or Ni to the basic AZ-31 composition reduced the corrosion rate at 150 deg by a factor of about two. Sn may be advantageously substituted for Zn in AZ-31. Control of the pH in the range between 6 and 7 and maintenance of a fluoride concentration in the range between 1 and 10 ppm reduced the corrosion rate of AZ-31 to about 0.1 mil per day at 150 deg C. (auth