The object of this program has been to evaluate the role of grain boundaries in the deformation and fracture behavior of beryllium. Utilizing bi-crystals grown by a parallel seed-floating zone technique, selected orientation configurations believed significant in polycrystalline deformation have been investigated. Features of flow and fracture in bi-crystals deformed in direct tests to failure and companion interrupted tests have been examined by optical microscopy as well as surface replication electron microscopy. Dislocation interactions at the boundary have been evaluated by electron transmission microscopy of thin foils. Brittle behavior was noted in the asymmetric and modified symmetric configurations investigated. Inability to accommodate mixed dislocation interactions, and complex grain rotations are believed responsible. In the absence of these adverse circumstances in a symmetric configuration, ductile behavior was observed. Other potentially ductile symmetric configurations should be evaluated to further clarify features of polycrystalline deformation. (Author).

Beryllium is a lightweight metal that is used for its exceptional strength and high heat-absorbing capability. Beryllium and its alloys can be found in many important technologies in the defense and aeronautics industries, such as nuclear devices, satellite systems, radar systems, and aircraft bushings and bearings. Pulmonary disease associated with exposure to beryllium has been recognized and studied since the early 1940s, and an occupational guideline for limiting exposure to beryllium has been in place since 1949. Over the last few decades, much has been learned about chronic beryllium disease and factors that contribute to its occurrence in exposed people. Despite reduced workplace exposure, chronic beryllium disease continues to occur. Those developments have led to debates about the adequacy of the long-standing occupational exposure limit for protecting worker health. This book, requested by the U.S. Air Force to help to determine the steps necessary to protect its workforce from the effects of beryllium used in military aerospace applications, reviews the scientific literature on beryllium and outlines an exposure and disease management program for its protecting workers.