Grain Boundary Diffusion and Segregation in Compacted and Sintered Nanocrystalline Alloys
- Title
- Grain Boundary Diffusion and Segregation in Compacted and Sintered Nanocrystalline Alloys
- Author
- 이재성
- Keywords
- Grain Boundary Diffusion; Interface Segregation; Nanocrystalline Alloy; Sintering
- Issue Date
- 2004-01
- Publisher
- Trans Tech Publications
- Citation
- Journal of Metastable and Nanocrystalline Materials, v. 19, Page. 55-68
- Abstract
- An overview of self- (Fe, Ni) and solute (Ag) tracer diffusion in the well-compacted and sintered nanocrystalline (grain size d∼100nm) γ-Fe-40wt. % Ni alloy is presented. In the nanocrystalline material the individual nano-scaled grains turned out to be clustered in micrometer-sized agglomerates and two types of internal interfaces with different length scales and diffusion characteristics (the boundaries between the nano-grains and between the agglomerates of these nanocrystallites) act as different short-circuit diffusion paths. A systematics of grain boundary (GB) self- and solute diffusion in such bimodal structure is outlined. Well-known Harrison's kinetic regimes of GB diffusion in a unimodal structure, i.e. the C, B, and A regimes are subdivided into the C-B, B-B, AB-B, and A-B regimes, which were observed experimentally. The theoretical framework to extract diffusivities of the nanocrystalline and inter-agglomerate boundaries from the multi-stage experimental profiles is presented. The combination of GB diffusion measurements of Ag solute diffusion in nano- and coarse-grained γ-FeNi alloys allowed to establish the segregation behavior of Ag. The absolute values and the Arrhenius parameters of Fe, Ni, and Ag diffusion along the nanocrystalline boundaries in the nano-γ-FeNi alloy are similar to the corresponding GB diffusivities in coarse-grained polycrystalline γ-FeNi. However, the activation enthalpy of diffusion along the inter-agglomerate boundaries turned out to be notably smaller and the absolute diffusivities larger by several orders of magnitude than the corresponding diffusion values via the nano-boundaries.
- URI
- https://repository.hanyang.ac.kr/handle/20.500.11754/132019https://www.scientific.net/JMNM.19.55
- ISSN
- 1422-6375
- DOI
- 10.4028/www.scientific.net/JMNM.19.55
- Appears in Collections:
- COLLEGE OF ENGINEERING SCIENCES[E](공학대학) > MATERIALS SCIENCE AND CHEMICAL ENGINEERING(재료화학공학과) > Articles
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