Interaction of Edge Dislocation With Stacking Fault Tetrahedron in Cu

This paper reports an anomaly in the yield strength of dislocation interacting with stacking fault tetrahedra (SFT) in Cu, reveals atomic mechanisms that are responsible for the anomaly, and further shows the thermodynamic driving force for the atomic mechanisms to prevail. Instead of monotonically increasing with the area of intersection cross-section, the yield strength first increases and then decreases with the area. The decrease, or the anomaly, is due to a change of atomic mechanism of the interactions—the SFT goes through a morphological transformation. The thermodynamic driving force for the transformation derives from the competition between the elastic energy of dislocations and the stacking fault energy.

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Dislocation-Stacking Fault Tetrahedron Interactions in Cu

Journal of Engineering Materials and Technology ◽

10.1115/1.1479692 ◽

2002 ◽

Vol 124 (3) ◽

pp. 329-334 ◽

Cited By ~ 95

Author(s):

B. D. Wirth ◽

V. V. Bulatov ◽

T. Diaz de la Rubia

Keyword(s):

Edge Dislocation ◽

Interatomic Potential ◽

High Energy ◽

Dislocation Motion ◽

Shear Localization ◽

Stacking Fault ◽

Dynamics Simulation ◽

High Energy Particle ◽

Face Centered Cubic ◽

Stacking Fault Tetrahedra

In copper and other face centered cubic metals, high-energy particle irradiation produces hardening and shear localization. Post-irradiation microstructural examination in Cu reveals that irradiation has produced a high number density of nanometer sized stacking fault tetrahedra. The resultant irradiation hardening and shear localization is commonly attributed to the interaction between stacking fault tetrahedra and mobile dislocations, although the mechanism of this interaction is unknown. In this work, we present results from a molecular dynamics simulation study to characterize the motion and velocity of edge dislocations at high strain rate and the interaction and fate of the moving edge dislocation with stacking fault tetrahedra in Cu using an EAM interatomic potential. The results show that a perfect SFT acts as a hard obstacle for dislocation motion and, although the SFT is sheared by the dislocation passage, it remains largely intact. However, our simulations show that an overlapping, truncated SFT is absorbed by the passage of an edge dislocation, resulting in dislocation climb and the formation of a pair of less mobile super-jogs on the dislocation.

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The construction of displacement fields of dislocation loops and stacking-fault tetrahedra from angular dislocation segments

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1979.0071 ◽

1979 ◽

Vol 292 (1397) ◽

pp. 513-521 ◽

Cited By ~ 15

Keyword(s):

Computer Simulation ◽

Stacking Fault ◽

Detailed Knowledge ◽

Image Simulation ◽

Dislocation Loops ◽

Displacement Fields ◽

Burgers Vector ◽

Stacking Fault Tetrahedra ◽

Microscope Images ◽

Stacking Fault Tetrahedron

The computer simulation of electron microscope images of lattice defects requires detailed knowledge of the displacement fields of the defects. By using the method of Yoffe (1960), expressions are derived for the displacement field of a regular N -sided polygonal dislocation loop of arbitrary Burgers vector, and of a stacking-fault tetrahedron, in forms suitable for use in image simulation.

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Contrast From Point Defects in The Infinitesimal Approximation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600001495 ◽

1980 ◽

Vol 38 ◽

pp. 350-351

Author(s):

L. J. Sykes ◽

J. J. Hren

Keyword(s):

Electron Microscope ◽

Point Defects ◽

Broad Class ◽

Stacking Fault ◽

Crystalline Solids ◽

Dislocation Loops ◽

Analytical Expression ◽

Stacking Fault Tetrahedra

In electron microscope studies of crystalline solids there is a broad class of very small objects which are imaged primarily by strain contrast. Typical examples include: dislocation loops, precipitates, stacking fault tetrahedra and voids. Such objects are very difficult to identify and measure because of the sensitivity of their image to a host of variables and a similarity in their images. A number of attempts have been made to publish contrast rules to help the microscopist sort out certain subclasses of such defects. For example, Ashby and Brown (1963) described semi-quantitative rules to understand small precipitates. Eyre et al. (1979) published a catalog of images for BCC dislocation loops. Katerbau (1976) described an analytical expression to help understand contrast from small defects. There are other publications as well.

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Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

Nonlinear Analysis Modelling and Control ◽

10.15388/na.2005.10.2.15129 ◽

2005 ◽

Vol 10 (2) ◽

pp. 151-160 ◽

Cited By ~ 3

Author(s):

J. Kala ◽

Z. Kala

Keyword(s):

Yield Strength ◽

Cross Section ◽

Carrying Capacity ◽

Bending Moment ◽

Statistical Characteristics ◽

Load Carrying Capacity ◽

Load Carrying ◽

Strength Variability ◽

Hot Rolled ◽

Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

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