TY - JOUR

T1 - Fourth-order strain-gradient phase mixture model for nanocrystalline fcc materials

AU - Klusemann, Benjamin

AU - Bargmann, Swantje

AU - Estrin, Yuri

PY - 2016/11/2

Y1 - 2016/11/2

N2 - The proposed modeling approach for nanocrystalline materials is an extension of the local phase mixture model introduced by Kim et al (2000 Acta Mater. 48 493-504). Local models cannot account for any non-uniformities or strain patterns, i.e. such models describe the behavior correctly only as long as it is homogeneous. In order to capture heterogeneities, the phase mixture model is augmented with gradient terms of higher order, namely second and fourth order. Different deformation mechanisms are assumed to operate in grain interior and grain boundaries concurrently. The deformation mechanism in grain boundaries is associated with diffusional mass transport along the boundaries, while in the grain interior dislocation glide as well as diffusion controlled mechanisms are considered. In particular, the mechanical response of nanostructured polycrystals is investigated. The model is capable of correctly predicting the transition of flow stress from Hall-Petch behavior in conventional grain size range to an inverse Hall-Petch relation in the nanocrystalline grain size range. The consideration of second- and fourth-order strain gradients allows non-uniformities within the strain field to represent strain patterns in combination with a regularization effect. Details of the numerical implementation are provided.

AB - The proposed modeling approach for nanocrystalline materials is an extension of the local phase mixture model introduced by Kim et al (2000 Acta Mater. 48 493-504). Local models cannot account for any non-uniformities or strain patterns, i.e. such models describe the behavior correctly only as long as it is homogeneous. In order to capture heterogeneities, the phase mixture model is augmented with gradient terms of higher order, namely second and fourth order. Different deformation mechanisms are assumed to operate in grain interior and grain boundaries concurrently. The deformation mechanism in grain boundaries is associated with diffusional mass transport along the boundaries, while in the grain interior dislocation glide as well as diffusion controlled mechanisms are considered. In particular, the mechanical response of nanostructured polycrystals is investigated. The model is capable of correctly predicting the transition of flow stress from Hall-Petch behavior in conventional grain size range to an inverse Hall-Petch relation in the nanocrystalline grain size range. The consideration of second- and fourth-order strain gradients allows non-uniformities within the strain field to represent strain patterns in combination with a regularization effect. Details of the numerical implementation are provided.

KW - Engineering

KW - Mechanik

KW - constitutive modeling

KW - gradient plasticity

KW - higher order gradient terms

KW - nanocrystalline material

KW - molecular-dynamics simulation

KW - dependant mechanical-behaviour

KW - hall-petch relationship

KW - grain-size dependence

KW - high-pressure torsion

KW - crystal plasticity

KW - deformation behavior

KW - metallic glasses

KW - rate sensitivity

KW - enhanced damage

KW - nanocrystalline material

KW - gradient plasticity

KW - higher order gradient terms

KW - constitutive modeling

UR - http://www.scopus.com/inward/record.url?scp=84995503641&partnerID=8YFLogxK

U2 - 10.1088/0965-0393/24/8/085016

DO - 10.1088/0965-0393/24/8/085016

M3 - Journal articles

AN - SCOPUS:84995503641

VL - 24

SP - 1

EP - 23

JO - Modelling and Simulation in Materials Science and Engineering

JF - Modelling and Simulation in Materials Science and Engineering

SN - 0965-0393

IS - 8

M1 - 085016

ER -