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Title: Self-diffusion and magnetic properties in explosion densified nanocrystalline Fe

Abstract

The enhanced diffusivity due to the high volume fraction of grain boundaries (GB's) is a key feature for the modified physical and chemical properties of nanocrystalline (n-) materials in contrast to the chemically identical coarse-grained solids. The authors previously performed tracer diffusion experiments on high-density n-Pd (relative density {rho}/{rho}{sub 0} {approximately} 97%, where {rho}{sub 0} is the theoretical density) and n-Fe ({rho}/{rho}{sub 0} {approximately} 92%) prepared by conventional static compaction of the gas-condensed powders at elevated temperatures, showing that the diffusivity of the n-metals is similar to the conventional GB diffusion in polycrystalline (poly-) metals. The specimens used in these studies, however, were not fully dense, with defects such as pores or cracks which may act as fast diffusion paths. The dynamic compaction technique utilizing the explosion or collide of a high speed projectile has also been applied for consolidation of fine powders of metals and ceramics. Recently, n-ceramics prepared by static pressing of fine powders were successfully further densified to more than 90% of the theoretical density by explosive compaction suppressing grain growth and contamination. In order to provide additional experimental information on interface structure and properties in n-metals, the density of n-Fe was further increased by explosive compactionmore » and effects of the densification on both self-diffusivity and bulk magnetic properties were examined.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Univ. of Tsukuba, Ibaraki (JP)
OSTI Identifier:
20075985
Resource Type:
Journal Article
Journal Name:
Scripta Materialia
Additional Journal Information:
Journal Volume: 42; Journal Issue: 10; Other Information: PBD: 10 May 2000; Journal ID: ISSN 1359-6462
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; SELF-DIFFUSION; MAGNETIC PROPERTIES; EXPLOSIVE FORMING; IRON; POWDERS; INTERFACES; GRAIN BOUNDARIES; DIFFUSION

Citation Formats

Tanimoto, H., Pasquini, L., Pruemmer, R., Kronmueller, H., and Schaefer, H.E. Self-diffusion and magnetic properties in explosion densified nanocrystalline Fe. United States: N. p., 2000. Web. doi:10.1016/S1359-6462(00)00326-2.
Tanimoto, H., Pasquini, L., Pruemmer, R., Kronmueller, H., & Schaefer, H.E. Self-diffusion and magnetic properties in explosion densified nanocrystalline Fe. United States. doi:10.1016/S1359-6462(00)00326-2.
Tanimoto, H., Pasquini, L., Pruemmer, R., Kronmueller, H., and Schaefer, H.E. Wed . "Self-diffusion and magnetic properties in explosion densified nanocrystalline Fe". United States. doi:10.1016/S1359-6462(00)00326-2.
@article{osti_20075985,
title = {Self-diffusion and magnetic properties in explosion densified nanocrystalline Fe},
author = {Tanimoto, H. and Pasquini, L. and Pruemmer, R. and Kronmueller, H. and Schaefer, H.E.},
abstractNote = {The enhanced diffusivity due to the high volume fraction of grain boundaries (GB's) is a key feature for the modified physical and chemical properties of nanocrystalline (n-) materials in contrast to the chemically identical coarse-grained solids. The authors previously performed tracer diffusion experiments on high-density n-Pd (relative density {rho}/{rho}{sub 0} {approximately} 97%, where {rho}{sub 0} is the theoretical density) and n-Fe ({rho}/{rho}{sub 0} {approximately} 92%) prepared by conventional static compaction of the gas-condensed powders at elevated temperatures, showing that the diffusivity of the n-metals is similar to the conventional GB diffusion in polycrystalline (poly-) metals. The specimens used in these studies, however, were not fully dense, with defects such as pores or cracks which may act as fast diffusion paths. The dynamic compaction technique utilizing the explosion or collide of a high speed projectile has also been applied for consolidation of fine powders of metals and ceramics. Recently, n-ceramics prepared by static pressing of fine powders were successfully further densified to more than 90% of the theoretical density by explosive compaction suppressing grain growth and contamination. In order to provide additional experimental information on interface structure and properties in n-metals, the density of n-Fe was further increased by explosive compaction and effects of the densification on both self-diffusivity and bulk magnetic properties were examined.},
doi = {10.1016/S1359-6462(00)00326-2},
journal = {Scripta Materialia},
issn = {1359-6462},
number = 10,
volume = 42,
place = {United States},
year = {2000},
month = {5}
}