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Science 12 October 2007:
Vol. 318. no. 5848, pp. 251 - 254
DOI: 10.1126/science.1143719
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Reports

Dislocation Avalanches, Strain Bursts, and the Problem of Plastic Forming at the Micrometer Scale

Ferenc F. Csikor,1,2 Christian Motz,3 Daniel Weygand,3 Michael Zaiser,2 Stefano Zapperi4,5*

Under stress, many crystalline materials exhibit irreversible plastic deformation caused by the motion of lattice dislocations. In plastically deformed microcrystals, internal dislocation avalanches lead to jumps in the stress-strain curves (strain bursts), whereas in macroscopic samples plasticity appears as a smooth process. By combining three-dimensional simulations of the dynamics of interacting dislocations with statistical analysis of the corresponding deformation behavior, we determined the distribution of strain changes during dislocation avalanches and established its dependence on microcrystal size. Our results suggest that for sample dimensions on the micrometer and submicrometer scale, large strain fluctuations may make it difficult to control the resulting shape in a plastic-forming process.

1 Department of Materials Physics, Eötvös University, Post Office Box 32, H-1518 Budapest, Hungary.
2 Center for Materials Science and Engineering, University of Edinburgh, King's Buildings, Sanderson Building, Edinburgh EH93JL, UK.
3 Universität Karlsruhe, Institut für die Zuverlässigkeit von Bauteilen und Systemen, Kaiserstrasse 12, 76131 Karlsruhe, Germany.
4 Consiglio Nazionale delle Ricerche–Istituto Nazionale per la Fisica della Materia, Statistical Mechanics and Complexity, Dipartimento di Fisica, Sapienza–Università di Roma, P.le A. Moro 2, 00185 Roma, Italy.
5 Institute for Scientific Interchange Foundation, Viale S. Severo 65, 10133 Torino, Italy.

* To whom correspondence should be addressed. E-mail: stefano.zapperi{at}roma1.infn.it

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Dislocation Mean Free Paths and Strain Hardening of Crystals.
B. Devincre, T. Hoc, and L. Kubin (2008)
Science 320, 1745-1748
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Science. ISSN 0036-8075 (print), 1095-9203 (online)