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Journal Articles Acta Materialia Year : 2009

Grain-size dependent accommodation due to intragranular distributions of dislocation loops

Abstract

A grain-size dependent accommodation law for polycrystals is deduced from an inclusion/matrix problem (i.e., each grain is seen as embedded in a homogeneous equivalent medium) where plastic strain inside the inclusion is given as a discrete distribution of circular coaxial glide dislocation loops. The loops are assumed constrained at spherical grain boundaries. From thermodynamic considerations specific to a process of identical plastification in all the loops (considered as “super-dislocations”), an average back-stress over the grain is derived. In order to compute the very early stages of plastic deformation in a face-centred cubic polycrystal, this back-stress is incorporated into a diluted model in terms of concentration of plastic grains. Contrary to conventional mean-field approaches, a grain-size effect is obtained for the initial overall strain-hardening behaviour. This size effect results from an intrinsic contribution of intragranular slip heterogeneities on the kinematical hardening.

Dates and versions

hal-03038498 , version 1 (03-12-2020)

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Thiebaud Richeton, S. Berbenni, M. Berveiller. Grain-size dependent accommodation due to intragranular distributions of dislocation loops. Acta Materialia, 2009, 57 (5), pp.1347-1356. ⟨10.1016/j.actamat.2008.11.024⟩. ⟨hal-03038498⟩
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