Journal
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
Volume 493, Issue 1-2, Pages 21-25Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2007.08.093
Keywords
dislocations; nano-scale plasticity; stress
Categories
Funding
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [0748267] Funding Source: National Science Foundation
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We compare mechanical strength of f.c.c. gold and b.c.c. molybdenum single crystal pillars of sub-micrometer diameter in uniaxial compression tests. Both crystals show an increase of flow stress with decreasing diameter, but the change is more pronounced in Au than in Mo. The ratio between the observed maximum flow stress and the theoretical strength is much larger in An pillars than in Mo pillars. Dislocation dynamics simulations also reveal different dislocation behavior in these two metals. While in a f.c.c. crystal a dislocation loop nucleated from the surface simply moves on its glide plane and exits the pillar, in a b.c.c. crystal it can generate multiple new dislocations due to the ease of screw dislocations to change slip planes. We postulate that this difference in dislocation behavior is the fundamental reason for the observed difference in the plastic deformation behavior of f.c.c. and b.c.c. pillars. (c) 2007 Elsevier B.V. All rights reserved.
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