Stability of binary nanocrystalline alloys against grain growth and phase separation
Journal Article
·
· Acta Materialia
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Materials Science and Engineering
Grain boundary segregation has been established through both simulation and experiments as a successful approach to stabilize nanocrystalline materials against grain growth. However, relatively few alloy systems have been studied in this context; these vary in their efficacy, and in many cases the stabilization effect is compromised by second phase precipitation. We address the open-ended design problem of how to select alloy systems that may be stable in a nanocrystalline state. We continue the development of a general “regular nanocrystalline solution” model to identify the conditions under which binary nanocrystalline alloy systems with positive heats of mixing are stable with respect to both grain growth (segregation removes the grain boundary energy penalty) and phase separation (the free energy of the nanocrystalline system is lower than the common tangent defining the bulk miscibility gap). We calculate a “nanostructure stability map” in terms of alloy thermodynamic parameters. Three main regions are delineated in these maps: one where grain boundary segregation does not result in a stabilized nanocrystalline structure, one in which macroscopic phase separation would be preferential (despite the presence of a nanocrystalline state stable against grain growth) and one for which the nanocrystalline state is stable against both grain growth and phase separation. Additional details about the stabilized structures are also presented in the map, which can be regarded as a tool for the design of stable nanocrystalline alloys.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- SC0001299
- OSTI ID:
- 1381964
- Alternate ID(s):
- OSTI ID: 1105288
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 6 Vol. 61; ISSN 1359-6454
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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