Dislocation modelling at atomistic and mesoscopic scales

Current Opinion in Solid State and Materials Science

Volumn 3, Issue 6, 1998, Pages 558-561

  Bulatov, Vasily V ^a   Kubin, Ladislas P ^b  

^a Massachusetts Institute of Technology Cambridge   (United States)

^b CNRS   (France)

Author keywords

F E Friedel Escaig; LC Lomer Cottrell

Indexed keywords

EID: 0000079193     PISSN: 13590286     EISSN: None     Source Type: Journal    
DOI: 10.1016/S1359-0286(98)80025-9     Document Type: Article

References (29)

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2. Rasmussen T, Jacobsen KW, Leffers T, Pedersen OB. Simulations of the atomic structure, energetics and cross-slip of screw dislocations in copper. of special interest Phys Rev B. 56:1997;2977-2990 A potential deriving from the effective medium theory is used, but it is fitted to a too high value of the stacking fault energy. Different configurations relevant to the F-E cross-slip mechanism are examined. The two half-constrictions are observed to have different energies, due to different local character of the partial dislocations. The 'screw' constriction even exhibits a negative energy (-1 eV). The annihilation of two screw dislocations of opposite sign and the behaviour of the dissociated dislocation close to a free surfece are also studied.
3. Bulatov VV, Yip S, Argon S. Atomic modes of dislocation mobility in silicon. Phil Mag. 72:1995;453-496.
4. Nastar M, Bulatov VV, Yip S. Saddle-point configurations for self-interstitial migration in silicon. Phys Rev B. 53:1996;13521-13527.
5. Duesbery MS. Dislocation motion, constriction and cross-slip in fcc metals. of outstanding interest Model Simul Mater Sci Eng. 6:1998;35-49 A Finnis-Sinclair potential for copper is used Cross-slip is found to always occur regardless of the state of constriction, which is in some analogy with an earlier model suggested by Fleischer. Rather large cross-slip stresses, from 0.02 to 0.06 μ (μ. shear modulus) are required, depending on the partial separation in the slip plane. Such a mechanism would exhibit a dependence on the local stress state completely different from that of the F-E model. Some intriguing observations about constriction distances and critical stresses for dislocation motion are also discussed.
6. Bulatov V, Abraham FF, Kubin L, Devincre B, Yip S. Connecting atomistic and mesoscale simulations crystal plasticity. of outstanding interest Nature. 391:1998;669-672 A Lennard-Jones potential was used for MD simulations of a fcc crystal of low stacking fault energy containing 100 million atoms. Under stress, the emission, and interaction of Schockley partials from an arrested crack was observed. The total (elastic plus core) energy of formation of the LC lock was computed at atomistic scale, from which the obstacle strength was estimated in a form scaled to the length of the parent mobile segment responsible for the unzipping process. This allowed rescaling of the obstacle length and a comparison of the obtained value with the current parameters of junction strength used in mesoscopic simulations.
7. Kubin LP, Devinore B, Tang M. Mesoscopic modelling and simulation of plasticity in fcc and bcc crystals: dislocation intersections and mobility. J Comput Aided Mater Design. 5:1998;1-24.
8. Baskes MI, Hoagland RG, Tsuji T. An atomistic study of the strength of an extended-dislocation barrier. Model Simul Mater Sci Eng. 6:1998;9-18.
9. Zhou SJ, Preston DL, Lomdhal PS, Beazley DM. Large-scale molecular dynamics simulations of dislocation intersection in copper. of outstanding interest Science. 279:1998;1525-1527 An embedded atom potential is used to simulate a copper crystal. Initially, two dissociated dislocations are positioned for a repulsive interaction perpendicular to each other. Then, as the two dislocations approach each other under the forcing stress, they twist and align themselves along the intersection line of the two glide planes so that at the point of contact the interaction becomes attractive an LC lock is formed. After unzipping of the lock, jog dragging the vacancy production are observed, although the jog is in principle glissile. The observed scenario does not depend on the system size, ranging from 200,000 to 3.5 million atoms, and on the forcing stress, from 395 MPa to 3.17 GPa.
10. Duesbery MS, Vitek V. Plastic anisotropy in bcc transition metals. of special interest Acta Mater. 46:1998;1481-1492 This overview focuses on the present state of understanding of non-Schmid effects, which is illustrated by Finnis-Sinclair type MD simulations of the core structure of the screw dislocations. It also gives a useful list of references to earlier work. In the first part, the concept of generalised stacking fault energy surface is used to obtain simple information about the dislocation cores and their properties. The second part focuses on the non-Schmid effects, categorised as intrinsic effects, inherent to the bcc structure, and extrinsic effects caused by external loading.
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12. Bulatov VV, Justo JF, Cai W, Yip S. Kink asymmetry and multiplicity in dislocation cores. of special interest Phys Rev Lett. 79:1997;5042-5045 It is shown that a complete set of possible core defects, kinks and solitons can be identified a priori, by considering symmetry properties of the core of a straight defect-free dislocation. Not only topological types, but also degeneracies of the core defects can be predicted, making the laborious task of evaluating the kink mechanisms of dislocation motion manageable even for some of the more complex dislocation core structures.
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14. Xu W, Moriarty JA. Accurate atomistic simulations of the Peierls barrier and kink-pair formation energy for <111> screw dislocation in bcc Mo. Comput Mater Sci. 9:1998;348-356.
15. Nunes RW, Bennetto J, Vanderbilt D. Atomic structure of dislocation kinks in silicon. Phys Rev B. 57:1998;10388-10397.
16. Devincre B. Meso-scale simulation of the dislocation dynamics. Kirchner HOK, Kubin LP, Pontikis V. Computer Simulation in Materials Science. 1996;309-323 Kluwer Academic Publishing, Dordrecht.
17. Zbib HM, Rhee M, Hirth JP. On plastic deformation and the dynamics of 3D dislocations. of outstanding interest Int J Mech Sci. 40:1998;113-127 Off-lattice segmentation of the dislocation lines enables the rigorous incorporation of the elastic properties of dislocations. Further development of this method requires more efficient algorithms to reduce the CPU (central processing unit) cost of treating large scale configurations.
18. Rodin GJ. Towards rapid evaluation of the elastic interactions among three-dimensional dislocations. Phil Mag Lett. 77:1998;187-190.
19. Devincre B, Kubin LP. Mesoscopic simulations of dislocations and plasticity. of outstanding interest Mater Sci Eng A. 234-236:1997;8-14 The applications of this simulation are divided in two groups depending on whether microstructures and mechanical properties are governed mainly by individual or by collective dislocation behaviour. Both large scale configurations and simple model situations are discussed.
20. Fivel MC, Gosling TJ, Canova GR. Implementing image stresses in a 3D dislocation simulation. Model Simul Mater Sci Eng. 4:1996;581-596.
21. Cleveringa HHM, van der Giessen E, Needleman A. Comparison of discrete dislocation and continuum plasticity predictions for a composite material. of special interest Acta Mater. 45:1997;3163-3179 Distributions and mean values of the internal stress, computed within the continuum and discrete frameworks, are shown not to match exactly. This poses the question of the compatibility between the continuum and dislocation approaches.
22. Fivel M, Verdier M, Canova G. 3D simulation of a nanoindentation test at a mesoscopic scale. of special interest Mater Sci Eng A. 234-236:1997;923-926 A finite element approach is used to solve the boundary value problem from which the stress field applied to the dislocations is derived. The mesoscopic code moves the dislocations until they reach an equilibrium position. Modified boundary conditions are then solved. This is the first attempt to impose in 3D complex boundary conditions within a coupled mesoscopic-continuum framework.
23. Tang M, Kubin LP, Canova GR. Dislocation mobility and the mechanical response of bcc single crystals: a mesoscopic approach. of special interest Acta Mater. 46:1998;3221-3235 This work illustrates the need for more input from an atomistic scale in order to set appropriate local rules in bcc metals. The connection between a mesoscopic mobility law for screw dislocations and the mechanical properties is established by simulating a thermal activation analysis of the global response of the model crystal.
24. Moulin A, Condat M, Kubin LP. Simulation of Frank-Read sources in silicon. Acta Mater. 45:1997;2339-2348.
25. Rhee M, Zbib HM, Hirth JP, Huang H, de la Rubia T. Models for long-short range interactions and cross-slip in 3D dislocation simulation of BCC single crystals. Model Simul Mater Sci Eng. 6:1998;1-26.
26. Devincre B, Veyssière P, Kubin LP, Saada GA. A simulation of dislocation dynamics and of the flow stress anomaly in L12 alloys. Phil Mag A. 75:1997;1263-1286.
27. Schwarz KW, LeGoues FK. Dislocation patterns in strained layers from sources on parallel glide planes. of outstanding interest Phys Rev Lett. 79:1997;1877-1880 The elastic interaction of dislocations concurrently emitted by two Frank-Read sources operating in two parallel slip planes leads to the formation of a rather complex configuration held together by strong elastic interactions. The resemblance with the observed network microstructures in strained layers is rather striking. The approach can be extended to account for purely elastic (i.e. without contact of the lines), but complex, interactions observed at short distances in atomistic simulations.
28. Raabe D. Introduction of a hybrid model for the discrete 3D simulation of dislocation dynamics. Comput Mater Sci. 11:1998;1-15.
29. Devincre B, Kubin LP. The modelling of dislocation dynamics: elastic behaviour versus core properties. Phil Trans R Soc Lond A. 355:1997;2003-2012.