Volume 68, Number 3, November 2004
|Page(s)||405 - 411|
|Section||Condensed matter: structure, mechanical and thermal properties|
|Published online||16 October 2004|
Twinning pathway in BCC molybdenum
Department of Nuclear Engineering, Massachusetts Institute of Technology Cambridge, MA 02139, USA
2 Handai Frontier Research Center, Osaka University - Osaka, Japan
3 Department of Mechanical Engineering and Systems, Osaka University Osaka 565-0871, Japan
4 Department of Materials Science and Engineering, Ohio State University Columbus, OH 43210, USA
5 Department of Materials Science and Engineering Massachusetts Institute of Technology - Cambridge, MA 02139, USA
Accepted: 27 August 2004
The twinning energy landscape of BCC is determined using the density functional theory for embryos containing 2 to 7 layers. The 2-layer embryo is metastable, whereas the 3- and 4-layer ones are unstable. Layer-by-layer growth starts at 5 layers. The twin boundary formation and migration energies are found to be 607 and 40, respectively, indicating that twin partial dislocations have wide cores and high mobilities. The stress to homogeneously nucleate an additional partial loop on the boundary of a sufficiently thick twin is only 1.4; this implies that once a deformation twin reaches critical thickness, which we estimate to be 6 layers, subsequent growth in thickness is easy.
PACS: 62.20.Fe – Deformation and plasticity (including yield, ductility, and superplasticity) / 61.72.Nn – Stacking faults and other planar or extended defects / 61.72.Mm – Grain and twin boundaries
© EDP Sciences, 2004
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