Stress-Corrosion Cracking of Al-Zn-Mg Alloys: The Corrosion Behavior of Grain Boundary Constituents

Since the grain-boundary constituents in Al-Zn-Mg alloys are generally too fine for their corrosion behavior to be studied in situ, an experimental approach involving simulation was adopted. This involved the examination of the corrosion behavior of a small ingot of MgZn2, the Al-Zn-Mg alloy in the as-quenched state, and pure aluminum. The pure aluminum and the as-quenched alloy were considered to represent the two limiting cases of the material comprising the precipitate-free zone pure aluminum representing the limiting case of the solute-depleted region and the as-quenched alloy the vacancy depleted region.