2469. Introduction of Beryllium Aluminum Castings in the RAH-66 Comanche EOSS Program

Paper

Abstract

Beryllium aluminum alloys, containing greater than 60 weight percent beryllium, are very attractive materials for lightweight and high-stiffness applications. However, due to the inherent problems associated with casting these alloys, processing of beryllium aluminum has generally been restricted to rolling and extrusion of pre-alloyed powder metal compacts. Starmet Corporation (formally Nuclear Metals, Inc.), with technical and financial support from the Lockheed Martin Electronics and Missiles (LMEM) RAH-66 Comanche Electro-Optical Sensor System (EOSS) program, has developed a family of castable beryllium aluminum alloys suited for production using state-of-the-technology investment casting processes. These new alloys, identified as Beralcast?, yield a fine grain homogenous microstructure with attractive mechanical, physical and thermal properties. The problems associated with producing beryllium aluminum castings, including molten metal reactivity and a wide solidification range, have been resolved. As a result of the efforts to date, over fifty different Comanche EOSS components of various sizes and complexities are being produced using Beralcast? alloys. In certain cases, where designs are being modified to take full advantage of the Beralcast? properties, component weight savings of up to 50% over conventional materials can be achieved. Current focus is on the optimization of castings and cost reduction. Developmental program goals, over the past few years, have been and are being addressed in a series of programs funded by Starmet Corporation, LMEM, and the Army Aviation Research and Development Center. As a result of these efforts, Beralcast? investment castings have been available in time to support the RAH-66 Comanche EOSS demonstration/validation (Dem/Val) night hardware program.