Dislocation avalanches, strain bursts, and the problem of plastic forming at the micrometer scale.
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.
Csikor
Ferenc F
FF
Department of Materials Physics, Eötvös University, Post Office Box 32, H-1518 Budapest, Hungary.
Motz
Christian
C
Weygand
Daniel
D
Zaiser
Michael
M
Zapperi
Stefano
S