scholarly journals Deformation pathway and defect generation in crystals: a combined group theory and graph theory description

IUCrJ ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 96-104 ◽  
Author(s):  
Yipeng Gao ◽  
Yunzhi Wang ◽  
Yongfeng Zhang
Keyword(s):  
Plastic Deformation ◽  
Graph Theory ◽  
Group Theory ◽  
Symmetry Breaking ◽  
Mathematical Framework ◽  
Face Centered Cubic ◽  
Systematic Determination ◽  
Face Centered ◽  
Pathway Graph

The generation and motion of crystalline defects during plastic deformation are critical processes that determine the mechanical properties of a crystal. The types of defect generated are not only related to the symmetry of a crystal but also associated with the symmetry-breaking process during deformation. Proposed here is a new mathematical framework to capture the intrinsic coupling between crystal symmetry and deformation-induced symmetry breaking. Using a combination of group theory and graph theory, a general approach is demonstrated for the systematic determination of the types of crystalline defect induced by plastic deformation, through the construction of a crystal deformation group and a deformation pathway graph. The types of defect generated in the deformation of a face-centered cubic crystal are analyzed through the deformation pathway graph and compared with experimental observations.

scholarly journals A New Set-Up to Investigate Plastic Deformation of Face Centered Cubic Metals in High Strain Rate Loading

2014 ◽  
Vol 8 (2) ◽  
Author(s):  
Ehsan Etemadi ◽  
Jamal Zamani ◽  
Alessandro Francesconi ◽  
Mohammad V. Mousavi ◽  
Cinzia Giacomuzzo
Keyword(s):  
Plastic Deformation ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Face Centered Cubic ◽  
Cubic Metals ◽  
Face Centered ◽  
Set Up ◽  
Strain Rate Loading

A modified Zerilli–Armstrong constitutive model for simulating severe plastic deformation of a steel alloy

2021 ◽  
pp. 095440542110609
Author(s):  
Muralimohan Gurusamy ◽  
Balkrishna C Rao
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Constitutive Relation ◽  
Orthogonal Cutting ◽  
Chip Morphology ◽  
Steel Alloy ◽  
Face Centered Cubic ◽  
Aisi 1045 Steel ◽  
Face Centered ◽  
1045 Steel

A modified Zerilli–Armstrong model has been proposed and validated in previous works for simulating distinct deformation mechanisms of continuous-shear and shear-localization during severe plastic deformation of a face centered cubic alloy. In this paper, the validity of the modified Zerilli–Armstrong model has been further tested by using it for modeling the severe plastic deformation of another face centered cubic material, a steel alloy. In particular, the modified Zerilli–Armstrong model is used as a constitutive relation for simulating behavior of AISI 1045 steel alloy while undergoing severe plastic deformation through orthogonal and plane-strain machining. Accordingly, the performance of the constitutive relation in predicting flow stress distribution along the primary shear zone is validated by comparing with forecasts made using the distributed primary zone deformation, the original Zerilli-Armstrong and Johnson-Cook models. Furthermore, finite element simulations of orthogonal cutting of this steel alloy were carried out, and good agreement was observed between the predicted chip morphology and attendant cutting forces with experimental values reported in literature for a range of cutting conditions. The force predictions also fared better compared to those predicted by using the Zerilli-Armstrong and Johnson-Cook models. These validations provide further corroboration of using the modified Zerilli–Armstrong model as a constitutive relation for simulating the behavior of face-centered cubic materials under conditions of high plastic strains and also high strain-rates.

Plastic Deformation of Nanometric Grinding Process for FCC Metal

2010 ◽  
Vol 154-155 ◽  
pp. 1336-1341
Author(s):  
Wei Wen Zhang ◽  
Gang Guo ◽  
Yun Huang ◽  
Zhi Huang
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Grinding Process ◽  
Face Centered Cubic ◽  
Grinding Processes ◽  
Cubic Structure ◽  
Simulation Results ◽  
Face Centered ◽  
Dislocation Defects ◽  
Fcc Metal

This paper focuses on the simulations of nanometric grinding process on face centered cubic structure (FCC) single metal crystals (Cu, Ni) using Molecular dynamics. In order to analyze the plastic deformation of sample metals in nanometric grinding processes, we propose an approach using techniques of central symmetry parameters and neighbor changing ratios. The simulation results show that besides the normal dislocation defects, weak slipping defects locating on {111} crystal planes are found under the surface layer. In addition, the distribution of the neighbor changing ratio indicates that the nano grinding processes will likely cause the global plastic deformation in the surface layer.

Experimental Determination of Dissolution Kinetics of Zr-Substituted Gd-Ti Pyrochlore Ceramics: Influence of Chemistry on Corrosion Resistance

2002 ◽  
Vol 757 ◽  
Author(s):  
Icenhower J.P. ◽  
Weber W.J. ◽  
Hess N.J. ◽  
Thevuthasen S. ◽  
Begg B.D. ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Dissolution Kinetics ◽  
Fluorite Structure ◽  
Annealed Specimen ◽  
Face Centered Cubic ◽  
Zirconium Content ◽  
The Face ◽  
Flow Through ◽  
Face Centered

ABSTRACTThe corrosion resistance of a series of zirconium-substituted gadolinium pyrochlore, Gd2(Ti1-x Zrx)2O7, where x = 0.0, 0.25, 0.50, 0.75, and 1.00, were evaluated using single-pass flow-through (SPFT) apparatus at 90°C and pH = 2. The zirconate end-member, Gd2Zr2O7, has a defect fluorite structure, which distinguishes it from the face-centered cubic structure of the true pyrochlore specimens. In addition to the chemical variation, the samples include annealed, un-annealed, and ion-bombarded monoliths. In the case of the titanate end-member, Gd2Ti2O7, the annealed specimen exhibited the least reactivity, followed by the un-annealed and ion-bombarded samples (2.39×10-3, 1.57×10-2, and 1.12×10-1 g m-2 d-1, respectively). With increasing zirconium content, the samples displayed less sensitivity to processing or surface modification with the zirconate end-member exhibiting no difference in reactivity between annealed, un-annealed, and ion-bombarded specimens (rate = 4.0×10-3 g m-2 d-1). In all cases, the dissolution rate decreased with increasing zirconium content to the Gd2(Ti0.25Zr0.75)2O7 composition (1.33x10-4 g m-2 d-1), but the zirconate end-member yielded rates nearly equal to that of the titanate end-member. These results demonstrate that to achieve the greatest radiation and corrosion resistance in this series, the Gd2(Ti0.25Zr0.75)2O7 composition should be considered.

The determination of solute atom displacements in mixed dumbbell interstitials for the face-centered-cubic lattice

1978 ◽  
Vol 56 (8) ◽  
pp. 1057-1070 ◽  
Author(s):  
N. Matsunami ◽  
M. L. Swanson ◽  
L. M. Howe
Keyword(s):  
Solute Atom ◽  
The Body ◽  
Continuum Approximation ◽  
Face Centered Cubic ◽  
Cubic Lattice ◽  
The Face ◽  
Solute Atoms ◽  
Face Centered ◽  
Small Solute

Interactions between irradiation-produced defects and solute atoms in metals have been investigated using the channeling technique. The interaction of interest in this investigation is the trapping of self interstitials by small solute atoms thus creating a [Formula: see text] mixed dumbbell, consisting of a host atom and a solute atom straddling a lattice site in the face-centered-cubic lattice. The displacement of solute atoms from lattice sites in the mixed dumbbell configuration was determined by comparing the experimentally observed normalized yields from solute atoms and from host atoms with the yields calculated analytically using the continuum approximation. The solute atoms in Al–Mn, Al–Cu, and Cu–Be mixed dumbbells were situated at 0.5 Å from the body-centered position, whereas the Ag atoms in Al–Ag dumbbells were 0.7 Å from this position. This result is consistent with the theoretical expectation that the smallest solute atoms are displaced the greatest amount in mixed dumbbells. In addition, experimentally obtained solute atom yields for [Formula: see text] and [Formula: see text] angular scans were compared with calculated scans. It was concluded that for large displacements of solute atoms into the flux peaking region, the analytical (continuum) calculation is a reliable method of determining solute atom displacements, either from the aligned yields or from the angular scans.

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