Influence of orientation on the size effect in BCC pillars with different critical temperatures.
- INM - Leibniz Institute for New Materials and Saarland University, SaarbrÞucken, Germany
- Karlsruhe Institute of Technology, Institut fÞur ZuverlÞassigkeit von Bauteilen und Systemen, Karlsruhe, Germany
- University of Wyoming, Laramie, WY
- Max Planck Institute for Metals Research, Stuttgart, Germany
The size effect in body-centered cubic metals is comprehensively investigated through micro/nano-compression tests performed on focused ion beam machined tungsten (W), molybdenum (Mo) and niobium (Nb) pillars, with single slip [2 3 5] and multiple slip [0 0 1] orientations. The results demonstrate that the stress-strain response is unaffected by the number of activated slip systems, indicating that dislocation-dislocation interaction is not a dominant mechanism for the observed diameter dependent yield strength and strain hardening. Furthermore, the limited mobility of screw dislocations, which is different for each material at ambient temperature, acts as an additional strengthening mechanism leading to a material dependent size effect. Nominal values and diameter dependence of the flow stress significantly deviate from studies on face-centered cubic metals. This is demonstrated by the correlation of size dependence with the material specific critical temperature. Activation volumes were found to decrease with decreasing pillar diameter further indicating that the influence of the screw dislocations decreases with smaller pillar diameter.
- Research Organization:
- Sandia National Laboratories
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1005040
- Report Number(s):
- SAND2010-6719J
- Journal Information:
- Proposed for publication in Materials Science and Engineering A., Journal Name: Proposed for publication in Materials Science and Engineering A. Journal Issue: 3 Vol. 528; ISSN 0921-5093; ISSN MSAPE3
- Country of Publication:
- United States
- Language:
- English
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