Abstract
A mesoscale model is introduced to study the dynamics of material defects lying at interface junctions. The proposed framework couples the dynamics of discrete dislocation and disclination lines. Disclinations are expected to be natural defects at interface junctions; their presence serving the purpose of accommodating discontinuities in rotation fields at material interface junctions. Crystallography-based rules are proposed to describe the kinematics of disclination motion. A discrete-continuous couple-stress framework, in which discrete defect lines are introduced as plastic eigenstrains and eigencurvatures, is proposed to explicitly follow the dynamics of interfacial defects. The framework is then applied to study left (10bar {1}2right) twin transverse propagation and thickening in magnesium. Focusing first on the case of a twin domain, It is shown that a disclination based representation of twin domains allows for an appropriate mechanistic description of the kinematics of shear transformations. In what concerns twin thickening, the stability of defects at twin interfaces is further studied. To this end, a 3D crater lying on a twin interface is described as a dipole of disclination loops. Upon self-relaxation, it is found that out of plane motion of disclinations followed by the nucleation of twinning dislocations can be activated; thereby showing that conservative non-planar motion of disclinations can be thermodynamically favorable; mechanism that had been postulated some 50 years ago.
Highlights
In the context of multi-scale modeling, the current performance of discrete dislocation dynamics (DDD) codes allows for a linkage between unit processes associated with dislocation motion -as informed by atomistic simulations- and their collective effects on both hardening and slip (Arsenlis et al 2007; Bulatov et al 1998; Devincre and Kubin 1997; Fivel and Canova 1999; Ghoniem et al 2000; Zbib et al 1998)
In addition to discrete dislocation lines, discrete disclination lines are introduced to account for the incompatibilty of elastic curvatures and discontinuity of elastic rotations in material interface defects, such as triple lines, twin tips, and interface ledges
Apart from the numerical implementation, our work proposes that disclinations could be intrinsic defects that are to be unambiguously found at junction between material interfaces
Summary
In the context of multi-scale modeling, the current performance of discrete dislocation dynamics (DDD) codes allows for a linkage between unit processes associated with dislocation motion -as informed by atomistic simulations- and their collective effects on both hardening and slip (Arsenlis et al 2007; Bulatov et al 1998; Devincre and Kubin 1997; Fivel and Canova 1999; Ghoniem et al 2000; Zbib et al 1998). The mechanical framework proposed considers line defects (i.e. dislocations and disclinations) both as discrete and as continuous objects. Assuming known the planes on which disclinations can move, to the case of dislocations, one can write the local incompatible plastic curvature field as follows: κipj i =
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
