Combined Experimental and Computational Study of Plastic Deformation in Crystals and Bicrystals for the Development of Multi-Length Scale Constitutive Models

摘要

The experimental effort concentrated on wedge indentation under quasistatic conditions in single crystals of Ni, Cu, and Al as well as bicrystals of Al. Wedge indenters with included angles of 60-deg, 90-deg, and 120-deg were used in the single crystals and an included angle of 90-deg was used near the train boundary of the Al bicrystal. the lattice rotations were experimentally determined via EBSD. The experimental results were processed to obtain all non-zero components of the Nye dislocation density tensor. An important advance was to derive the analytical expression for the Lower Bounds on the geometrically necessary dislocation density based upon the measured Nye dislocation density tensor associated with the two-dimensional deformation state.