The Peierls stress in a simple cubic lattice

Autor(en)

Gunther Schöck

Abstrakt

Dislocations aligned along close-packed directions in a crystal lattice experience when moving periodic variations of their energy with the period of the lattice cell. This can be described in the framework of the Peierls model when the generalized stacking-fault energy in the glide plane - the gamma-surface - has been derived. The maximum energy variation is called the Peierls energy E(P). As consequence of these energy variations there exists also a finite stress - the Peierls stress sigma(P) - necessary to displace a straight dislocations over the distance of a lattice cell without the aid of thermal fluctuations. It is commonly assumed that these energy variations result from changes in the atomic misfit energy E(A) in the glide plane and as consequence sP is defined by the maximum gradient of E(A). This assumption is inconsistent, however. When the dislocation moves in isothermal thermodynamic equilibrium the width w of the dislocation changes during displacement. An increase in misfit energy E(A) by an increase in width w is overcompensated by a corresponding decrease in elastic energy E(el). As result the variation in total energy - the Peierls energy - will be smaller as compared to the situation where no structural relaxation occurs during the movement.

Organisation(en)

Physik Nanostrukturierter Materialien

Externe Organisation(en)

Universität Wien

Journal

Physica Status Solidi. B: Basic Research

Band

248

Seiten

2284-2289

Anzahl der Seiten

6

ISSN

0370-1972

DOI

https://doi.org/10.1002/pssb.201147081

Publikationsdatum

2011

Peer-reviewed

Ja

ÖFOS 2012

103018 Materialphysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/af024fe2-39ff-4c7a-9e48-1cbdb10833bf