Nanocrystalline iron sintering behavior and microstructural development
- Univ. of Texas, Austin, TX (United States). Center for Materials Science and Engineering
- DLR Inst. for Materials Research, Cologne (Germany)
Nanocrystalline (20 nm) iron powder was closed-die sintered in a hydrogen atmosphere at a stress of 10.1 MPa and at temperatures between 670 and 1270 K. The maximum densification rate was approximately 6 [times] 10[sup [minus]4] s[sup [minus]1]. Density greater than 90 pct was obtained at sintering temperatures greater than 990 K. Densification was marked microstructurally by local gradients which appeared after initial cold compaction. Oxygen content in the starting powder was high but was effectively a monolayer of surface adsorbed oxygen. Despite the reducing sintering atmosphere, oxide was present in dense specimens as a fine dispersion of order 0.1 to 1 [mu]m. The extent of oxide formation can be controlled by closed-die sintering to a stable structure of interconnected porosity followed by open-die resintering in the reducing atmosphere. Final grain size in material sintered 1 hour at 1,080 K was generally less than 200 nm, although scattered coarsening to approximately 5 [mu]m was observed.
- OSTI ID:
- 7175908
- Journal Information:
- Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 25:4; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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