Aluminum-lithium-beryllium alloys have been prepared by melt spinning, using prealloyed arc-melted buttons. The alloy ribbon was comminuted and cold compacted to 30 to 50% density, vacuum hot pressed to 100% density, and extruded. The bar product was subsequently solution heat treated, quenched, and aged. The microstructure of the alloys consists of a relatively featureless matrix containing a homogeneous dispersion of fine beryllium particles, mostly 50 to 500 nm in size. The results of heat treatment show that the alloys respond to age hardening in a manner similar to that of binary Al-Li alloys. Preliminary results on the mechanical properties and their relationships with microstructural features are presented for the Al-Li-Be alloys, as well as their potential for weight savings. The authors estimate that these monolithic aluminum alloys may exhibit specific strength and elastic modulus values comparable to those of the best whisker or particulate metal-matrix composites, while showing concomitant high weight savings.
A need exists within the aerospace industry for the engineering properties promised by aluminum alloys produced by rapid solidification technology (RST). The extent to which these alloys will achieve technical and commercial success depends, however, upon (1) achievement of the engineering property goals, (2) the degree of success in the development of competitive materials, including other aluminum products, and (3) the economics of using such alloys for any given application, including the total production, fabrication, and life cycle costs for the material. Useful applications of the new RST aluminum alloys are envisioned for each of the three primary groups of aerospace vehicles: aircraft, missiles, and space vehicles. Each of these groups has a different general set of material property and cost objectives. The current powder metallurgy (PM) aluminum alloy development efforts for aerospace applications can be divided conveniently into three categories or classes of alloys: (1) high-strength, corrosion-resistant alloys; (2) low-density, high-modulus alloys; and (3) elevated-temperature, creep-resistant alloys. The development objectives for each of these alloy categories depend on the specific needs of the aerospace market for that category. The current status of progress in the development of the RST aluminum alloys indicates that some technical and economic success will be achieved in each category. The extent of this success is yet to be established. An assessment of various factors that affect the future course of development for these materials is presented.
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