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The stability of a metal when exposed to a given environment depends on a multitude of factors that may vary greatly with the pH and oxidizing or reducing power f that environment. One useful concept to represent the effects of aqueous environments on metals became known as potential-pH (E-pH) diagrams, also called predominance or Pourbaix diagrams, which have been adopted universally since their introduction in late 1940's.
E-pH diagrams are typically plotted for various equilibria on normal Cartesian coordinates with potential (E) as the ordinate (Y axis) and pH as the abscissa (X axis). The major uses of such diagrams, which can be constructed for all metals, are: (reference)
Predicting whether or not corrosion can occur
Estimating the composition of the corrosion products formed
Predicting environmental changes which will prevent or reduce corrosion attack
