The Influence of Ca and Y on the Microstructure and Corrosion Resistance of Vacuum Die Casting AZ91 Alloy

The influence of Ca and Y on the microstructure and corrosion resistance of vacuum die casting AZ91 alloy is investigated using optical microscope, electron scanning microscope, weight-loss test and electrochemical corrosion test. The results indicate that the microstructure of AZ91 alloy can be refined, amount of Mg17Al12 phases is reduced, making Mg17Al12 phases transform from banding to reticular, and stringer Al2Ca phases and block Al2Y phases are formed through adding both Ca and Y. The corrosion resistance of AZ91 magnesium alloy can be increased greatly by adding both Ca and Y. The corrosion rate of AZ91-1.5Ca-1.0Y alloy is dropped to 16.2% of that of AZ91 alloy immersed in 3.5% NaCl aqueous solution for 24 hours. The corrosion current density of AZ91-1.5Ca-1.0Y alloy is dropped by one order of magnitude.
Comment: 9 pages, 7 figuers, 4 tables