Stability criteria for nanocrystalline alloys
Alloying nanocrystalline materials to stabilize them against grain growth is proving a critical enabling strategy for the processing and usage of bulk nanocrystalline parts. Alloying elements that segregate strongly to grain boundaries can lead to a preference for nanocrystalline structure, and to b...
| Main Authors: | , |
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| Other Authors: | , |
| Format: | Article |
| Language: | English |
| Published: |
Elsevier BV,
2020-01-27T21:17:06Z.
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| Subjects: | |
| Online Access: | Get fulltext |
| Summary: | Alloying nanocrystalline materials to stabilize them against grain growth is proving a critical enabling strategy for the processing and usage of bulk nanocrystalline parts. Alloying elements that segregate strongly to grain boundaries can lead to a preference for nanocrystalline structure, and to be most stable the grain boundary segregated state would need to be preferred to forming any other phase or solute configuration, including a solid solution, ordered compounds, or solute precipitates. In this paper, a stability criterion is developed by comparing the enthalpy of the grain boundary segregated state against such stable bulk phases. This enthalpic criterion is also translated into a lattice model framework to enable the use of Monte Carlo simulations to incorporate entropic and geometric effects in assessing nanocrystalline stability. Monte Carlo simulations show that entropy can play a role in stabilizing nanocrystalline states, leading to duplex structures, and also in forming a grain boundary network preferentially over a disordered or amorphous-like bulk phase. Keywords: Nanocrystalline; Alloy; Grain boundary; Segregation; Intermetallic United States. Army Research Office (Grant W911NF-14-1-0539) |
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