Neutron diffraction study of the deformation behavior of beryllium–aluminum composites

Abstract

Neutron diffraction measurements of the mean phase elastic strains during loading were performed on two different beryllium–aluminum composites. The first was Be–47.5Al–2.5Ag produced from hot isostatically pressed powder fabricated by rapid solidification using a centrifugal atomization process; the second was a commercially available Be–38Al extruded powder product. Under rapid solidification, Be–Al undergoes liquid phase separation, resulting in a three-dimensional interpenetrating morphology in which both phases are continuous. Elastic strains in the individual phases were measured as a function of tensile and compressive load at the Los Alamos Neutron Scattering Center using a pulsed neutron source. The deformation behavior was unusual due to the unique composite microstructure and elastic properties of beryllium. Notably, the aluminum developed compressive elastic strains in the direction perpendicular to the compressive loading axis. These strains were compared with predictions from finite element analyses to clarify the stress state in each phase during deformation.