Ductility in intermetallic compounds

Intermetallic compounds are comprised of two or more metallic elements, but unlike ordinary metals, they have bonding that is part metallic, part covalent, and part ionic. Because of their mixed bonding, they are often lighter, stronger, stiffer, and more corrosion-resistant than ordinary metals, particularly at high temperatures. Yet their uses are limited because they are usually brittle at room temperature (RT), making them difficult to fabricate and vulnerable to fracture. These materials hold great promise to improve efficiency in the transportation, electric power generation, and chemical process industries; however, persistent problems with low ductility and poor fracture toughness have severely limited their use in engineering systems. This article presents an overview of the progress in improving the RT ductility and fracture toughness of intermetallic compounds and describes prospects for their near-term engineering use.