Athermal Mechanisms of Size-Dependent Crystal Flow Gleaned from Three-Dimensional Discrete Dislocation Simulations
Abstract
Recent experimental studies discovered that micrometer-scale face-centered cubic crystals show strong strengthening effects, even at high initial dislocation densities. We use large-scale 3-D discrete dislocation simulations (DDS) to explicitly model the deformation behavior of FCC Ni microcrystals in the size range 0.5 to 20 microns. The study shows that two size-sensitive thermal hardening processes, beyond forest hardening, are sufficient to develop the dimensional scaling of the flow stress, stochastic stress variation, flow intermittency and high initial strain-hardening rates, similar to experimental observations for various materials. One mechanism, source-truncation hardening, is especially potent in micrometer-scale volumes. A second mechanism, termed exhaustion hardening, results from a breakdown of the mean-field conditions for forest hardening in small volumes, thus biasing the statistics of ordinary dislocation processes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2008
- Accession Number
- ADA490438
Entities
People
- C. E. Woodward
- Dennis M. Dimiduk
- M. D. Uchic
- Mingchu Tang
- S.I. Rao
- Triplicane A. Parthasarathy
Organizations
- Universal Energy Systems