Why sodium Hydroxide Solution Cannot Be Kept In Aluminium Containers?

Sodium Hydroxide in contact with some metals ( Aluminium , Magnesium , Zinc ) reacts to produce flammable and potentially explosive Hydrgen Gas. Aluminium is actually a very reactive metal that is unusual as it has layer of oxide ( Al2O3 ) on the surface. This oxide is soluble in base forming an aluminate exposing the Aluminium surface which reacts.