U N C L A S S I F I E D Preliminary Analysis of Deformation of Beryllium in a Non-Uniform Stress Field T.A. Sisneros 1, D. W. Brown 1, B. Clausen 1, C.M. Cady 1, G.T. Gray III 1, E. Tulk 1 and J. Almer 2 1 Los Alamos National Laboratory, Los Alamos, New Mexico 2 Argonne National Laboratory, Argonne, Illinois ABSTRACT An experimental investigation was carried out to study the stress (strain) state and dominant deformation mode in the gage section of shear compression specimens (SCS) of both textured and randomly textured polycrystalline beryllium. Due to the low crystal symmetry, beryllium, like most other hexagonal metals, must deform using a host of deformation modes, including dislocation slip and mechanical twinning, as consequence, beryllium is very brittle in tension at room temperature. SCS have two opposed slots machined at 45º with respect to the longitudinal axis, thus forming the test gage section. Beryllium samples with a distinct starting texture were deformed in-situ at strain rates of /sec and 1/sec. The spatial variation of the lattice strains over the gauge section was measured in situ using synchrotron X-ray diffraction. The analysis is ongoing therefore, at this time we report that significant ductility, as well as twinning activity was observed in the textured material.

U N C L A S S I F I E D Measurements on 1-ID at Advanced Photon Source Beam from monochromator 0.1x0.1mm beam Slits Sample Diffracted beam   X-ray energy = 65KeV. Beam cross section: 100  m X 100  m Collection time: seconds. Precision translation and rotation stages for mapping. 15kN load frame. ~1200C furnace.

U N C L A S S I F I E D We use in-situ diffraction to learn about deformation

U N C L A S S I F I E D Beryllium is brittle at room temperature in tension, ductility was observed in shear SampleHeightWidthThicknessWeb heightWeb thickness 22°C, 0.001/s °C, 1/s

U N C L A S S I F I E D Deformed Slow Post -deformation Pre-deformation Post-deformation Basal peak intensity begins to increase markedly from the initial value, signaling the detection of deformation twins Deformed Fast Post -deformation Pre-deformation Normalized basal pole intensities (002) along the loading direction (Long.) Deformation twins