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College Park, Maryland      June 6 - 10 , 2004

W2-A2 (2:00 PM): The use of neutron diffraction and polycrystal plasticity modeling to understand deformation in hexagonal metals.

D. W. Brown, M. A. M. Bourke, W.R. Blumenthal, S.C. Vogel, C. N. Tome (Los Alamos National Laboratory), T. M. Holden (Northern Stress Technologies), K. Conlon (Chalk River), S.R. Agnew (Universtiy of Virginia)

Due to the high crystallographic symmetry of body-centered and face-centered cubic metals, plastic deformation is relatively simple because one unique slip mode can provide arbitrary deformation. This is not true in lower symmetry hexagonal metals, where prismatic and basal slip (the usual favored modes) are insufficient to provide arbitrary deformation. Often, either pyramidal slip and/or deformation twinning must be activated to accommodate the imposed plastic deformation. The varied difficulty of activating each of these deformation mechanisms results in highly anisotropic yield surface and subsequent mechanical properties. Further, the incipient activity of each deformation mode may be manipulated through control of the crystallographic texture, opening new opportunities for the optimization of mechanical properties for a given application. This talk will highlight studies done by several researchers at the neutron scattering center at Los Alamos over the past two years focused on the combined use of neutron diffraction measurements and computational modeling to understand micro-mechanical deformation mechanisms in hexagonal metals, in particular Be, Mg, Ti, and Zr.

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