Origin of Brittle Cleavage in Iridium
Abstract
Iridium is unique among the face-centered cubic metals in that it undergoes brittle cleavage after a period of plastic deformation under tensile stress. Atomistic simulation using a quantum-mechanically derived bond-order potential shows that in iridium, two core structures for the screw dislocation are possible: a glissile planar core and a metastable nonplanar core. Transformation between the two core structures is athermal and leads to exceptionally high rates of cross slip during plastic deformation. Associated with this athermal cross slip is an exponential increase in the dislocation density and strong work hardening from which brittle cleavage is a natural consequence.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Aug 12, 2005
- Source ID
- 10.1126/science.1114704
Entities
People
- Christopher Woodward
- David G. Pettifor
- Duc Nguyen-manh
- Marc J Cawkwell
- Vaclav Vitek
Organizations
- Air Force Research Laboratory
- European Atomic Energy Community
- Northwestern University
- University of Oxford
- University of Pennsylvania