Magnesium aluminide is an intermetallic compound of magnesium and aluminum.Common phases (molecular structures) include beta phase (Mg2Al3) and gamma phase (Mg17Al12), both of which have a cubic crystal structure.Magnesium aluminide is an important component of 5XXX aluminum alloy (aluminum-magnesium alloy) and magnesium-aluminum alloy, which determines many of their engineering properties.Magnesium aluminide has the advantages of low density and high strength, and plays an important role in aero-engines.MgAl has also been investigated as a reactant to produce metal hydrides in hydrogen storage technologies.Like many intermetallic compounds,MgAl compounds often have unusual stoichiometry, with large and complex unit cells.

Hydride 

In chemistry, a hydride is formally the anion of hydrogen (H−).The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is the hydride of oxygen, ammonia is the hydride of nitrogen, etc.For inorganic chemists, hydrides refer to compounds in which hydrogen is covalently bound and ions to less electronegative elements.In this case, the H center has a nucleophilic character, in contrast to the protic character of an acid.Hydride anions are rarely observed.Almost all elements form binary compounds with hydrogen, except He,Ne, Ar, Kr, Pm, Os, Ir, Rn, Fr, and also made exotic molecules such as positron hydrides.

Applications

• Hydrides such as sodium borohydride, lithium aluminum hydride, diisobutylaluminum hydride (DIBAL) and super hydride are commonly used as reducing agents in chemical synthesis. Hydrides are added to the electrophilic center, usually an  unsaturated carbon.

• Hydrides such as sodium hydride and potassium hydride are used as strong bases in organic synthesis.The hydride reacts with a weakly protic acid to release H2.

• Hydrides such as calcium hydride are used as desiccants, ie desiccants, to remove traces of moisture from organic solvents. Hydrides react with water to form hydrogen and hydroxide salts.The dry solvent can then be distilled or vacuum transferred from the "solvent tank".

• Hydrides are important in battery technology, eg NiMH batteries.Various metal hydrides have been investigated as means of hydrogen storage for fuel cell electric vehicles and for other purposes of the hydrogen economy.

• Hydride complexes are catalysts and catalytic intermediates in various homogeneous and heterogeneous catalytic cycles. Important examples include hydrogenation, hydroformylation, hydrosilylation, hydrodesulfurization catalysts.Even certain enzymes, such as hydrogenases, function through hydride intermediates.Energy carrier nicotinamide adenine dinucleotide as  a hydride donor or hydride reaction.