Recent research on friction stir welding of aluminum structures has demonstrated that this process produces high strength joints in all aluminum alloys. This research will expand the use of this solid state joining technique to particle reinforced composites. This process involves minimal surface preparation and can be adapted to produce joints in almost any configuration. Complex spacecraft structures can be joined with a minimum of jigging and other capital expenses. The joiningprocess is currently being heavily investigated by Rockwell, Boeing, Lockheed and Martin for producing aluminum structures for spacecrafts. Structures such as the aluminum-lithium external fuel tanks are prime candidates for this process. The welding research is being done in conjunction with The Welding Institute, which holds the basic patents for the process. This project will team with the Rockwell International Science Center to produce the joints with their equipment and license for the process, the Materials Science Department of the Universityfor materials analysis with MMC Engineering and our understanding of the production and processing of these composites.The process involvesthe movement of a rotating pin between the pieces to be joined. The size and shape of the pin will be adapted to allow this process to produce high strength joints in particulate reinforced aluminum composites. The friction heating in the process is localized and no reaction between the particles and the matrix alloy will take place. This will insure that the high strength of the composite will be retained duringthe joining process. This program will develop on understanding of the material's response to this joining technique.
