Evolution of in-grain orientation gradient in plastically strained particulate materials

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The in-grain orientation gradient and grain fragmentation are essential features of substructure development under cold deformation up to large strains. In the previous study [P. Trivedi, D.P. Field, H. Weiland, Alloying effects on dislocation substructure evolution of aluminum alloys, Int. J. Plasticity 20 (2004) 459-476], we showed that the Mg and Si elements can influence the development of dislocation structures. The present study extends the above-mentioned work to the materials where effective hardening particles are distributed throughout the polycrystalline structure, and the interaction of dislocation substructures and these particles is significant. We focus upon the small strain regime and compare the in-grain orientation gradient of a precipitation hardened aluminum alloy as a function of precipitate morphologies during deformation. The precipitate morphologies were characterized using transmission electron microscopy, and the dislocation structure was analyzed using electron backscatter diffraction analysis of deformed specimens. The results clearly show that the deformation response was a function of the precipitate characteristics. Although, grain fragmentation increased during deformation, the effect of precipitates on the in-grain orientation gradient, and dislocation substructure evolution was more pronounced in the presence of semi-coherent β″ precipitates. This investigation offers motivation to include the precipitate parameters in the deformation framework of physics based computational modeling of crystals containing hardening particles. © 2009.

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Materials Science and Engineering A