Abstract

High temperature alloys are combinations of metals used specifically for their heat resisting properties. Applications in the aircraft, automotive, power generation, and space-related industries include use in steam and gas turbine engines, as cutting tools, and as various spacecraft parts.

The alloys most often used at high temperatures include steels, superalloys, refractory metal alloys, and intermetallic compounds. These alloys, their properties and surface stability, mechanical behavior, the strengthening mechanisms and process systems employed are discussed.

Various low alloy steels and wrought stainless steels are employed as are modified stainless steels. Superalloys may have, for example, nickel, cobalt, or iron-nickel bases. Nickel continues to be the preferred alloy base for high temperature alloys. The reasons for this is that nickel lacks an allotropic phase transformation below its melting point, it has a high tolerance for a wide variety of alloying elements without causing any phase stability, its close-packed face-centered cubic crystal structure, and the ability to produce and manipulate a very stable precipitate, which is one of the primary sources of elevated temperature strength in Ni-base alloys.