Structure of grain boundaries in nanocrystalline palladium by molecular dynamics simulation

Journal Article · Fri Aug 20 04:00:00 EDT 1999 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(99)00142-6· OSTI ID:691320

Keblinski, P; Wolf, D; Phillpot, S R ^[1]; Gleiter, H ^[2]

---

1. Argonne National Lab., IL (United States). Materials Science Div.
2. Forschungszentrum Karlsruhe (Germany)

The atomic structures of the grain boundaries (GBs) in nanocrystalline materials and their effect on properties have been the subject of extensive discussion ever since the first ultrafine-grained polycrystals were synthesized by consolidation of small clusters formed via gas condensation. A key question that has emerged is whether and under what conditions the atomic structure of the GBs in nanocrystalline materials can be extrapolated from those of coarse-grained polycrystalline materials and bicrystals. To address this question directly, in recent years computer simulation methods capable of providing structural information on the GBs in nanocrystalline microstructures have been developed; this type of local information is not readily available from experiments, such as x-ray diffraction studies, which provide only average structural information on these highly inhomogeneous materials. One such method uses molecular dynamics (MD) simulations to grow fully dense nanocrystalline microstructures from a melt into which small crystalline seeds with more or less random orientations are inserted. For the case of silicon as a model material, these simulations have enabled the authors to elucidate the connection between the GBs present in the nanocrystalline microstructure and the structure of bicrystalline GBs. In this paper, the authors present the results of a similar comparison for the case of face-centered cubic (fcc) metals. By contrast with their earlier simulations involving a generic fcc-metal (Lennard-Jones) interatomic potential, here they study palladium as a model fcc metal, with atomic interactions described by an embedded-atom-method (EAM) potential. Their choice of Pd is motivated by the significant amount of experimental data on the structure, mechanical and thermodynamic properties of nanocrystalline Pd, including self-diffusion and phonon properties. As in Si, these results suggest that a nanocrystalline microstructure with random grain orientations contains only high-energy GBs.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 691320
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 6 Vol. 41; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPUTERIZED SIMULATION
DIFFUSION
GRAIN BOUNDARIES
GRAIN ORIENTATION
MOLECULAR DYNAMICS METHOD
PALLADIUM