Atomistic Simulations for Multiscale Modeling in bcc Metals

1999 ◽  
Vol 121 (2) ◽  
pp. 120-125 ◽  
Author(s):  
John A. Moriarty ◽  
Wei Xu ◽  
Per So¨derlind ◽  
James Belak ◽  
Lin H. Yang ◽  
...  
Keyword(s):  
Multiscale Modeling ◽  
Strength Properties ◽  
Peierls Stress ◽  
Boundary Structure ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
Ideal Strength ◽  
Bcc Metals ◽  
Kink Pair ◽  
Grain Boundary Structure

Quantum-based atomistic simulations are being used to study fundamental deformation and defect properties relevant to the multiscale modeling of plasticity in bcc metals at both ambient and extreme conditions. Ab initio electronic-structure calculations on the elastic and ideal-strength properties of Ta and Mo help constrain and validate many-body interatomic potentials used to study grain boundaries and dislocations. The predicted Σ5 (310) [100] grain boundary structure for Mo has recently been confirmed in HREM measurements. The core structure, γ surfaces, Peierls stress, and kink-pair formation energies associated with the motion of a/2〈111〉 screw dislocations in Ta and Mo have also been calculated. Dislocation mobility and dislocation junction formation and breaking are currently under investigation.

scholarly journals Electronic Effects on Grain Boundary Structure in Bcc Metals

1999 ◽  
Vol 589 ◽  
Author(s):  
Geoffrey H. Campbell ◽  
Wayne E. King ◽  
James Belak ◽  
John A. Moriarty ◽  
Stephen M. Foiles
Keyword(s):  
Crystal Structure ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Structure ◽  
Atomistic Simulations ◽  
Dominant Factor ◽  
Interatomic Potentials ◽  
Electronic Effects ◽  
Bcc Metals ◽  
Grain Boundary Structure

AbstractThe dominant factor in determining the atomic structure of grain boundaries is the crystal structure of the material, e.g. FCC vs. BCC. However, for a given crystal structure, the structure of grain boundaries can be influenced by electronic effects unique to the element comprising the crystal. Understanding and modeling the influence of electronic structure on defect structures is a key ingredient for successful atomistic simulations of materials with more complicated crystal structures than FCC. We have found that grain boundary structure is a critical test for interatomic potentials. To that end, we have fabricated the nominally identical Σ5 (310)/[001] symmetric tilt grain boundary in three different BCC metals (Nb, Mo, and Ta) by diffusion bonding precisely oriented single crystals. The structure of these boundaries have been determined by high resolution transmission electron microscopy. The boundaries have been found to have different atomic structures. The structures of these boundaries have been modeled with atomistic simulations using inter-atomic potentials incorporating angularly dependent d–state interactions, as obtained from Model Generalized Pseudopotential Theory. We report here new experimental and theoretical results for Ta

Predicting grain boundary structure and energy in BCC metals by integrated atomistic and phase-field modeling

2019 ◽  
Vol 164 ◽  
pp. 799-809 ◽  
Author(s):  
Di Qiu ◽  
Pengyang Zhao ◽  
Chen Shen ◽  
Weijie Lu ◽  
Di Zhang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Phase Field ◽  
Boundary Structure ◽  
Phase Field Modeling ◽  
Bcc Metals ◽  
Field Modeling ◽  
Grain Boundary Structure

Peierls Stresses Estimated from CRSS Vs. Temperature Curve and their Relation to the Crystal Structure

2011 ◽  
Vol 465 ◽  
pp. 97-100 ◽  
Author(s):  
Yasushi Kamimura ◽  
Keiichi Edagawa ◽  
Shin Takeuchi
Keyword(s):  
Crystal Structure ◽  
B Value ◽  
Pair Formation ◽  
Temperature Curve ◽  
Peierls Stress ◽  
Material Parameters ◽  
Bcc Metals ◽  
Kink Pair ◽  
Data Points ◽  
Critical Resolved Shear Stress

Peierls stresses P of a variety of pure crystals, bcc metals, NaCl type crystals, elemental and compound tetrahedrally coordinated crystals, intermetallic compounds and ceramic crystals, have been estimated from the critical resolved shear stress (c) vs. temperature curves. For high P crystals where CRSS data are available only at high temperatures, P has been estimated from the critical temperature T0 at which steep temperature dependence of c vanishes: T0 is related to the kink-pair formation energy which is a function of P, material parameters and dislocation character controlling the deformation. The estimated p/G values are semi-log plotted against h/b value, where G is the shear modulus, h the slip plane spacing and b the Burgers vector. Two facts should be noted. First, P/G values for a group of crystals with the same crystal structure are within a range of a factor of 10. Second, most of the data points lie in between the classical Peierls-Nabarro relation and the Huntington’s modified relation. These facts indicates that Peierls stress is primarily determined by the crystal structure.

Nanocrystalline fcc metals: bridging experiments with simulations

2004 ◽  
Vol 821 ◽  
Author(s):  
H. Van Swygenhoven ◽  
P. M. Derlet ◽  
A. G. Frøseth ◽  
S. Van Petegem ◽  
Z. Budrovic ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Spatial Scales ◽  
Research Field ◽  
Boundary Structure ◽  
Atomistic Simulations ◽  
Clear Understanding ◽  
Structural Characterisation ◽  
Grain Boundary Structure ◽  
Deformation Processes

AbstractAtomistic simulations have provided unprecedented insight into the structural and mechanical properties of nanocrystalline materials, highlighting the role of the non-equilibrium grain boundary structure in both inter- and intra-grains deformation processes. One of the most important results is the capability of the nanosized grain boundary to act as a source and sink for dislocations. However the extrapolation of this knowledge to the experimental regime requires a clear understanding of the temporal and spatial scales of the modelling technique and a detailed structural characterisation of the simulated samples. In this contribution some of the synergies that can be developed between atomistic simulations and experiments for this research field are briefly discussed by means of some typical examples.

Nanocrystalline fcc metals: bridging experiments with simulations

2004 ◽  
Vol 819 ◽  
Author(s):  
H. Van Swygenhoven ◽  
P. M. Derlet ◽  
A. G. Frøseth ◽  
S. Van Petegem ◽  
Z. Budrovic ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Spatial Scales ◽  
Research Field ◽  
Boundary Structure ◽  
Atomistic Simulations ◽  
Clear Understanding ◽  
Structural Characterisation ◽  
Grain Boundary Structure ◽  
Deformation Processes

AbstractAtomistic simulations have provided unprecedented insight into the structural and mechanical properties of nanocrystalline materials, highlighting the role of the non-equilibrium grain boundary structure in both inter- and intra-grains deformation processes. One of the most important results is the capability of the nanosized grain boundary to act as a source and sink for dislocations. However the extrapolation of this knowledge to the experimental regime requires a clear understanding of the temporal and spatial scales of the modelling technique and a detailed structural characterisation of the simulated samples. In this contribution some of the synergies that can be develo ped between atomistic simulations and experiments for this research field are briefly discussed by means of some typical examples.

Two Investigations into Grain Boundary Structure

1977 ◽  
Vol 35 ◽  
pp. 688-691
Author(s):  
P. Humble
Keyword(s):  
Grain Boundary ◽  
Dark Field ◽  
Boundary Structure ◽  
Boundary Dislocation ◽  
Bright Field ◽  
Intrinsic Structure ◽  
Weak Beam ◽  
Grain Boundary Structure ◽  
Independent Information ◽  
Diffraction Patterns

There has been sustained interest over the last few years into both the intrinsic (primary and secondary) structure of grain boundaries and the extrinsic structure e.g. the interaction of matrix dislocations with the boundary. Most of the investigations carried out by electron microscopy have involved only the use of information contained in the transmitted image (bright field, dark field, weak beam etc.). Whilst these imaging modes are appropriate to the cases of relatively coarse intrinsic or extrinsic grain boundary dislocation structures, it is apparent that in principle (and indeed in practice, e.g. (1)-(3)) the diffraction patterns from the boundary can give extra independent information about the fine scale periodic intrinsic structure of the boundary.In this paper I shall describe one investigation into each type of structure using the appropriate method of obtaining the necessary information which has been carried out recently at Tribophysics.

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