LAUSR

The corrosion behavior for several die-cast Mg-Al alloys (AM50, AM50, and AZ91) was compared to commercial purity Mg and AZ31B-H24 utilizing simultaneous measurement of electrochemical impedance spectroscopy (EIS), hydrogen gas collection over a 24 h immersion period, gravimetric mass loss, and inductively coupled plasma optical emission spectrometry (ICP-OES) solution analysis of the total Mg concentration released. Tests were conducted in three electrolytes, unbuffered 0.6 M NaCl, 0.1 M tris(hydroxymethyl)aminomethane (TRIS), and 0.6 M NaCl buffered with TRIS to a pH of 7. EIS derived polarization resistance was monitored periodically, as determined from EIS circuit modeling using data collected to 0.001 Hz, and considering the pseudo-inductive low-frequency impedance time constant. EIS derived corrosion rates and oxidation charge density were similar to charge density determined from cumulative mass loss, ICP-OES solution analysis, and the volume of hydrogen collected for the die-cast AM50, AM60, and A...