ALUMINUM SUPERALLOYS FOR USE IN HIGH TEMPERATURE APPLICATIONS

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Aluminum-zirconium and aluminum-zirconium-lanthanide superalloys are described that can be used in high temperature, high stress and a variety of other applications. The lanthanide is preferably holmium, erbium, thulium or ytterbium, most preferably erbium. Also, methods of making the aforementioned alloys are disclosed. The superalloys, which have commercially-suitable hardness at temperatures above about 220°C, include nanoscale A13Zr precipitates and optionally nanoscale A13Er precipitates and nanoscale A13(Zr, Er) precipitates that create a high-strength alloy capable of withstanding intense heat conditions. These nanoscale precipitates have a L12-structure in a-A1(f.c.c) matrix, an average diameter of less than about 20 nanometers ("nm"), preferably less than about 10 nm, and more preferably about 4-6 nm and a high number density, which for example, is larger than about 1021 m-3, of the nanoscale precipitates. The formation of the high number density of nanoscale precipitates is thought to be due to the addition of inoculant, such as a Group 3A, 4A, and 5A metal or metalloid. Additionally, methods for increasing the diffusivity of Zr in A1 are disclosed.