Characterization of Mechanically Processed, Compacted and Heat Treated Nitrogenated bcc-Iron Powder

“…[3,4]. The X-ray analysis has shown that nanostructure with the grain size of approximately 10 nm is developed in the Fe-C-powder mechanically alloyed in a gaseous argon environment.…”

Section: Introductionmentioning

confidence: 98%

Mössbauer and X-ray studies of Fe-powder mechanically alloyed with C using power ultrasonics

et al. 2004

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“…The dispersoids are formed in situ during cryomilling by the co-adsorption of nitrogen and oxygen onto clean aluminum surfaces. The advantages of cryogenic milling include [12][13][14][15] reduced oxygen contamination from the atmosphere; faster convective heat transfer from the particles to the cryogenic media, which results in a lower particle temperature that favors fracturing over welding of ductile materials during the milling process; reduced milling time to achieve nanograins (hindering of microstructural recovery due to low temperature); and higher thermal stability of the material, attributed to pinning effects arising from the presence of oxy-nitride particles (dispersoids) formed during cryomilling. [16,17] Powder metallurgy consolidation techniques (e.g., cold isostatic pressure, hot isostatic pressure, extrusion, and variations of these) and thermal spray processes (e.g., high velocity oxygen-fuel (HVOF) spray and plasma spray) of the mechanically milled powders have been successfully used for synthesizing nanocrystalline alloys in bulk and coating forms, respectively.…”

Section: Introductionmentioning

confidence: 99%

Cold spray deposition of nanocrystalline aluminum alloys

Ajdelsztajn

Jodoin

Kim

et al. 2005

Metall Mater Trans A

205

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Aluminum 5083 powder was mechanically milled under liquid nitrogen to achieve a nanocrystalline grain size in the range of 20 to 30 nm. The powder was subsequently sprayed using a nozzle designed with a validated numerical model for cold spray technology. The resulting coatings were evaluated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro-and nanoindentation. The TEM analysis shows that the nanocrystalline grain structure of the cryomilled feedstock powder was retained after the cold spray process. A significant increase in hardness from 104 to 261 Ϯ 8 (HV 300g ) was observed when comparing the nanocrystalline coating with cast, coldworked, Al 5083. The ability to use cold spray to produce nanocrystalline large deposits was also demonstrated in this work.

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“…These studies have led to several important observations. The advantages of cryogenic milling include [25][26][27][28] reduced oxygen contamination from the atmosphere; faster convective heat transfer from the particles to the cryogenic media, which results in a lower particle temperature that favors fracturing over welding of ductile materials during the milling process; reduced milling time to achieve nanograins (hindering of microstructural recovery due to low temperature); and higher thermal stability of the material, attributed to pinning effects arising from the presence of oxynitride particles (dispersoids) formed during cryomilling. [21,22] Second, the minimum grain size obtainable by milling scales inversely with melting temperature [22][23][24] or the bulk modulus, B.…”

Section: Introductionmentioning

confidence: 99%

Spark plasma sintering of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy

Zúñiga

Ajdelsztajn

Lavernia

2006

Metall Mater Trans A

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The microstructure and aging behavior of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy was studied. The nanocrystalline powders were produced by milling at liquid nitrogen temperature and then consolidated using spark plasma sintering (SPS). The microstructure after SPS consisted of a bimodal aluminum grain structure (coarse-grained and fine-grained regions), along with Al 9 FeNi and Al 2 CuMg particles dispersed throughout. The microstructure observed in the as-consolidated sample is rationalized on the basis of high current densities that are generated during sintering. Solution treatment and aging of the SPS Al-Cu-Mg-Fe-Ni-Sc sample resulted in softening instead of hardening. This observation can be explained by the reduced amount of Cu, Mg, and Si in solid solution available to form S9 Al 2 CuMg due to the precipitation of Al 7 FeCu 2 and Si-rich particles, and by the fact that rodlike S9 Al 2 CuMg particles could only precipitate out in the coarse-grained regions, greatly decreasing their influence on the hardness. This lack of precipitation in the fine-grained region is argued to represent a new physical observation and is rationalized on the basis of physical and thermodynamic effects. The nanocrystalline SPS Al-Cu-Mg-Fe-Ni-Sc sample was also extremely thermally stable, retaining a fine-grained structure even after solution treatment at 530°C for 5 h. The observed thermal stability is rationalized on the basis of solute drag and Zener pinning caused by the impurities introduced during the cryomilling process.

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Characterization of Mechanically Processed, Compacted and Heat Treated Nitrogenated bcc-Iron Powder

Cited by 6 publications

References 0 publications

Mössbauer and X-ray studies of Fe-powder mechanically alloyed with C using power ultrasonics

Mössbauer and X-ray studies of Fe-powder mechanically alloyed with C using power ultrasonics

Cold spray deposition of nanocrystalline aluminum alloys

Spark plasma sintering of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy

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