The physical and mechanical properties of beryllium, especially the combina- tion of low density and high elastic modulus, make it an attractive candidate for a structural material. Intrinsic problems exist with Be as a monolithic material, as its structural behavior is complex due to its hexagonal close-packed crystal structure. Therefore, great value may be found in investigating composites of Be, such as beryllium-aluminum. However, one needs to understand the behavior of the individual phases in a Be composite and their interaction during the sequence of elasticity, plasticity, and fracture. The approach taken in this dissertation wasraction to monitor the elastic loading of each phase, in combination with detailed studies of the composite's mechanical behavior for strains up to 5 percent. In addition, the experiments were performed on a unique type of composite microstructure. This consisted of interpenetrating phases formed from liquid immiscibility, rather than conventional powder processing, which is limited by reactions at interfaces. The results were interpreted in terms of plasticity models and finite element calculations that describe the interaction between the phases and the local stress states established by compatibility requirements between the phases.
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