Definition - What does Alkaline mean?
This is a term that describes the state of an environment or solution that is alkali in nature and whose pH is greater than 7.
Metals that form simple positive ions (+2) in water to form hydrides, and result in a pH of more than 7, are called alkaline metals. Therefore, any basic material in this group that dissolves in water may result in an alkaline solution. They exist mostly as salts or oxides; they are termed as the most reactive materials in the periodic table. Basically, an alkaline material is found in composite minerals.
Corrosionpedia explains Alkaline
The alkaline earth metals are found in group II A in the periodic chart. They are reactive but not as reactive as the ones in group I A. The difference between the alkali metals and the alkaline earth metals is the valence. Other properties that can distinguish them are based on the melting and boiling temperatures, where the alkaline metals have high values.
Corrosion in metals will be felt in the presence of an alkaline solution since there are free ions, willing to react. Therefore, in the presence of oxygen and moisture, it leads to rusting in ferrous and non-ferrous materials. Alkaline environments are found to affect steel, zinc, and aluminum. Alkaline solutions are leading factors that lead to the formation of pitting and crevice corrosion in metals.