Author(s)

M. Brocato, P. Tamagny, A. Ehrlacher

Abstract

Moving grain boundaries in polycrystals M. Brocato\ P. Tamagny^ & A. Ehrlacher^ Abstract We model polycrystals as Cosserat continua and focus on the three independent mechanisms working at the boundary of grains: glide, growth (progression of the discontinuity front), and relative rotation of lattices. We propose a criterion and a flow rule for the three mentioned phenomena, then we introduce some constitutive assumptions and derive some new results on the relative spin of contiguous lattices. 1 Introduction At the scale of optical microscopy, cold-forming metals look like aggregates of grains. The crystal lattice appears almost uniform in the bulk of each grain, while no crystallographic directions can be observed on very sharp transition re- gions between grains. As grains may grow or sinter, these interfaces—the grain boundaries—do not necessarily move like material elements: the lattice rotation is an independent kinematic unknown of the problem. This picture

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