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High-temperature strength of compacted sub-micrometer aluminium powder / C. Poletti in Acta materialia, Vol. 58 N° 10 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3781–3789 Titre : High-temperature strength of compacted sub-micrometer aluminium powder Type de document : texte imprimé Auteurs : C. Poletti, Auteur ; M. Balog, Auteur ; F. Simancik, Auteur Année de publication : 2011 Article en page(s) : pp. 3781–3789 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Powder  consolidation  Aluminium  Ultrafine-grained  microstructure  High-temperature  deformation  Grain  boundary  structure Résumé : Aluminium powders with a mean particle size of around 1 μm were compacted by cold isostatic pressing (CIP) and additional forging. The specimens are characterized by hot compression tests, dilatometry and metallography. A 3D interconnected structure of alumina films <5 nm in thickness is observed by transmission electron microscopy and field emission gun scanning electron microscopy; it is associated with the natural oxide skin which covers every aluminium powder and occupies around 3 vol.%. The compression tests are carried out in the range of 350–520 °C at strain rates of 0.003–3 s−1. The compressive strength was 100–150 and 130–180 MPa for the CIPed and forged samples, respectively. The low strain rate sensitivity m (<0.08) suggests that the alumina network forms a barrier, which suppresses any restoration mechanism across the grain boundaries as well as grain boundary sliding during hot deformation. The high strength of such compacted sub-micron Al powder is attributed to the conservation of a 3D alumina closed cell network filled with elastoplastic aluminium. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001667 [article] High-temperature strength of compacted sub-micrometer aluminium powder [texte imprimé] / C. Poletti, Auteur ; M. Balog, Auteur ; F. Simancik, Auteur . - 2011 . - pp. 3781–3789. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3781–3789 Mots-clés : Powder  consolidation  Aluminium  Ultrafine-grained  microstructure  High-temperature  deformation  Grain  boundary  structure Résumé : Aluminium powders with a mean particle size of around 1 μm were compacted by cold isostatic pressing (CIP) and additional forging. The specimens are characterized by hot compression tests, dilatometry and metallography. A 3D interconnected structure of alumina films <5 nm in thickness is observed by transmission electron microscopy and field emission gun scanning electron microscopy; it is associated with the natural oxide skin which covers every aluminium powder and occupies around 3 vol.%. The compression tests are carried out in the range of 350–520 °C at strain rates of 0.003–3 s−1. The compressive strength was 100–150 and 130–180 MPa for the CIPed and forged samples, respectively. The low strain rate sensitivity m (<0.08) suggests that the alumina network forms a barrier, which suppresses any restoration mechanism across the grain boundaries as well as grain boundary sliding during hot deformation. The high strength of such compacted sub-micron Al powder is attributed to the conservation of a 3D alumina closed cell network filled with elastoplastic aluminium. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001667