A Theory of the Peierls Stress of a Screw Dislocation. I

1974 ◽  
Vol 36 (1) ◽  
pp. 187-195 ◽  
Author(s):  
Shunya Ishioka
Keyword(s):  
Screw Dislocation ◽  
Peierls Stress

Core energy and Peierls stress of a screw dislocation in bcc molybdenum: A periodic-cell tight-binding study

2004 ◽  
Vol 70 (10) ◽  
Author(s):  
Ju Li ◽  
Cai-Zhuang Wang ◽  
Jin-Peng Chang ◽  
Wei Cai ◽  
Vasily V. Bulatov ◽  
...  
Keyword(s):  
Screw Dislocation ◽  
Tight Binding ◽  
Binding Study ◽  
Peierls Stress ◽  
Periodic Cell ◽  
Core Energy

On non-glide stresses and their influence on the screw dislocation core in body-centred cubic metals I. The Peierls stress

1984 ◽  
Vol 392 (1802) ◽  
pp. 145-173 ◽  
Keyword(s):  
Screw Dislocation ◽  
Applied Stress ◽  
Strong Dependence ◽  
Dislocation Core ◽  
Peierls Stress ◽  
Exact Nature ◽  
Theoretical Shear Strength ◽  
Stress Variation ◽  
Cubic Model ◽  
Model Lattice

The response of the screw dislocation core in a body-centred cubic model lattice to a general applied stress tensor is examined by means of computer simulation. The Peierls stress is found to have the symmetry required by Neumann’s principle but is found also to have a very strong dependence on shear components of the applied stress which should not interact with the screw dislocation. Rather than having the constant value suggested by the Schmid law of critical resolved shear stress, the Peierls stress can vary from zero to the theoretical shear strength of the lattice, depending upon the exact nature of the critical applied stress components. Calculations with different interatomic binding potentials show that the Peierls stress variation, while different in detail, remains broadly the same, suggesting an origin in the dislocation core geometry rather than the specific charac­teristics of the force laws. Specialization to the case of uniaxial applied stress shows that the similar Peierls stress variation can nevertheless lead to quite different orientation dependences of the flow stress in different materials. Applications to the problem of brittle fracture and possible sources of the Peierls stress variation are discussed briefly.

Temperature and Stress Dependence of Mobility of Screw Dislocation in BCC Iron

2016 ◽  
Vol 258 ◽  
pp. 17-20
Author(s):  
Hideki Mori
Keyword(s):  
Screw Dislocation ◽  
Unit Length ◽  
Peierls Stress ◽  
Body Centered Cubic ◽  
Entropy Term ◽  
Energy Gradient ◽  
Bcc Iron ◽  
Peierls Barrier ◽  
Entropic Effect ◽  
Increasing Temperature

The Peierls stress and barrier of a screw dislocation in body-centered cubic iron at finite temperature is investigated by using the free energy gradient method. The Peierls barrier is shown to decrease from 12 to 5 meV per unit length of the Burgers vector with increasing temperature from 0 to 400 K. The entropy term of the Peierls barrier is estimated to be 0.2kB. The Peierls stress also decreases from 900 to 400 MPa with increasing temperature from 0 to 300 K. The change in the Peierls stress due to the entropic effect is larger than that of the Peierls barrier because of thermal softening.

scholarly journals Peierls stress of a screw dislocation in a piezoelectric medium

2004 ◽  
Vol 85 (12) ◽  
pp. 2211-2213 ◽  
Author(s):  
Shaofan Li ◽  
Anurag Gupta
Keyword(s):  
Screw Dislocation ◽  
Peierls Stress ◽  
Piezoelectric Medium

Molecular Dynamics Simulation of Interaction between Screw Dislocation and Copper Precipitate in Iron

2008 ◽  
Vol 33-37 ◽  
pp. 895-900 ◽  
Author(s):  
Akiyuki Takahashi ◽  
Yuji Aoki ◽  
Masanori Kikuchi
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulation ◽  
Screw Dislocation ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Peierls Stress ◽  
Attractive Interaction ◽  
Good Prediction ◽  
Critical Resolved Shear Stress

This paper provides the results of the MD simulations of the interaction between a screw dislocation and a copper precipitate in iron. From the results, the screw dislocation has an attractive interaction with the copper precipitate. Also, the dependence of the Critical Resolved Shear Stress (CRSS) for the screw dislocation to break away from the copper precipitate on the size of the precipitate and temperature is studied. Finally, the CRSS obtained by the MD simulations is modeled statistically using a Russel-Brown model. Then we found that an addition of the Peierls stress, which is calculated by the MD simulations, to the Russel-Brown model gives a good prediction of the CRSS.

On non-glide stresses and their influence on the screw dislocation core in body-centred cubic metals. II. The core structure

1984 ◽  
Vol 392 (1802) ◽  
pp. 175-197 ◽  
Keyword(s):  
Stress Tensor ◽  
Screw Dislocation ◽  
Applied Stress ◽  
Elastic Strain ◽  
Elastic Anisotropy ◽  
Dislocation Core ◽  
Core Structure ◽  
Peierls Stress ◽  
The Core ◽  
Anisotropic Elastic

The change in core structure of the screw dislocation in a body-centred cubic lattice subjected to a general applied stress tensor is studied by means of computer simulation. The large variations observed are found not to be correlated with the applied stress, in that the same deformed core structure can be realized by many different combinations of stress components. Instead, the core structure is found to be characterized almost exclusively by the magnitude and orientation of the induced glide strain, with a much smaller dependence on the glide stress. This means that while the force acting on a dislocation is defined by the applied stress, it is the elastic strain within the lattice that determines the resistance to motion. This explains the anomalously large dependence of the Peierls stress upon non-glide components of the applied stress tensor. The Peierls stress varies strongly with the shape of the dislocation core, which depends upon the glide strain. However, the glide strain is in turn dependent on non-glide components of the applied stress by way of anisotropic elastic couplings. Therefore the Peierls stress is itself dependent on the non-glide stresses, to an extent governed by the elastic anisotropy. The possible origin of the strain-dependence of the core structure in elastic strain multiplet forces (equal and opposite generalized forces acting on the dislocation) is discussed briefly, as are implications for the phenomenon of ductile fracture.

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