Dynamic consolidation of metastable nanocrystalline powders

Korth, G.E.; Williamson, R.L.

doi:10.1007/bf02669415

Cited by 48 publications

(14 citation statements)

References 16 publications

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“…However, recrystallization and graingrowth occur readily during high temperature consolidation of nanocrystalline powders, particularly those prepared from the MA process. In this regard, shock wave compaction is attractive because it can be used to fully densify powdered materials without inducing activated microstructural and compositional changes [237,238]. The characteristic features of the shock-wave deformation are high pressure (e.g.…”

Section: Consolidation From Nanocrystalline Powdersmentioning

confidence: 99%

“…Thus, shock compaction can produce high compressive stresses during short time periods, thereby heavily deforming the particles, melting the surfaces, and producing a fully dense compact without grain growth. Various guns and explosive detonation methods have been developed and used for shock compaction and shock synthesis of bulk nanocrystalline materials [238][239][240][241][242][243][244][245].…”

Section: Consolidation From Nanocrystalline Powdersmentioning

confidence: 99%

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Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

835

345

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In recent years, near-nano (submicron) and nanostructured materials have attracted increasingly more attention from the materials community. Nanocrystalline materials are characterized by a microstructural length or grain size of up to about 100 nm. Materials having grain size of $0.1 to 0.3 mm are classified as submicron materials. Nanocrystalline materials exhibit various shapes or forms, and possess unique chemical, physical or mechanical properties. When the grain size is below a critical value ($10-20 nm), more than 50 vol.% of atoms is associated with grain boundaries or interfacial boundaries. In this respect, dislocation pile-ups cannot form, and the Hall-Petch relationship for conventional coarse-grained materials is no longer valid. Therefore, grain boundaries play a major role in the deformation of nanocrystalline materials. Nanocrystalline materials exhibit creep and super plasticity at lower temperatures than conventional micro-grained counterparts. Similarly, plastic deformation of nanocrystalline coatings is considered to be associated with grain boundary sliding assisted by grain boundary diffusion or rotation. In this review paper, current developments in fabrication, microstructure, physical and mechanical properties of nanocrystalline materials and coatings will be addressed. Particular attention is paid to the properties of transition metal nitride nanocrystalline films formed by ion beam assisted deposition process. #

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Section: Consolidation From Nanocrystalline Powdersmentioning

confidence: 99%

Section: Consolidation From Nanocrystalline Powdersmentioning

confidence: 99%

Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

835

345

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“…Shock consolidation was the most effective method in minimizing the grain growth during consolidation. This is because the powder experienced very high pressures of a few GPa for a short duration of a few microseconds [21]. This high-strain rate deformation results in the generation of very high temperatures (sometimes above the melting point of the powder) at the surfaces of the powder particles.…”

Section: Shock Consolidationmentioning

confidence: 98%

Consolidation of nanocrystalline powders

Suryanarayana

Korth

1999

Metals and Materials

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Blended elemental Ti-24Al-llNb (at.%) and Ti-55A1 (at,%) powders were mechanically alloyed and consolidated to full density by hot isostatic pressing (H]Ping), Ceracon processing, and shock consolidation methods. Nanometer-sized grains were observed in all the samples, the finest size achieved in the shock-consolidated samples. The grain size was larger at higher HIPing temperatures. In comparison with conventional coarsegrained material, the HIP temperature for full consolidation could be brought down by about 400~ for the nanostructured titanium aluminides.

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“…Not much work has been carried out to consolidate mechanically alloyed (MAed) powders into bulk form. MAed powders can be consolidated by several methods such as, vacuum hot pressing [6,7], explosive compaction [7,8], spark plasma sintering [9], hot conventional extrusion [10,11], hot hydrostatic extrusion [12], and hot isostatic pressing [7,8]. A new processing route for the consolidation of MAed nanocrystalline 80Ni-15Fe-5Co (wt.%) powder has been proposed in the present investigation.…”

Section: Introductionmentioning

confidence: 97%