Metals
A good metallic fuel resists air oxidation and moisture, has a high heat output per gram, and is obtainable at moderate cost in fine particle sizes. Aluminum and magnesium are the most widely used materials. Titanium, zirconium, and tungsten are also used, especially in military applications.
The alkali and alkaline earth metals - such as sodium, potassium, barium, and calcium -- would make excellent high-energy fuels, but, except for magnesium, they are too reactive with moisture and atmospheric oxygen. Sodium metal, for example, reacts violently with water and must be stored in an inert organic liquid, such as xylene, to minimize decomposition.
A metal can initially be screened for pyrotechnic possibilities by an examination of its standard reduction potential. A readily oxidizable material will have a large, negative value, meaning it possesses little tendency to gain electrons and a significant tendency to lose them. Good metallic fuels will also be reasonably lightweight, producing high calories / gram values when oxidized. Table lists some of the common metallic fuels and their properties.
Properties of Metallic Fuels