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Fabrication, structure and mechanical properties of indium nanopillars / Gyuhyon Lee in Acta materialia, Vol. 58 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 4 (Fevrier 2010) . - pp. 1361–1368 Titre : Fabrication, structure and mechanical properties of indium nanopillars Type de document : texte imprimé Auteurs : Gyuhyon Lee, Auteur ; Ju-Young Kim, Auteur ; Arief Suriadi Budiman, Auteur Année de publication : 2011 Article en page(s) : pp. 1361–1368 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Plastic  deformation  X-ray  diffraction  Compression  test  Electroplating  Yield  phenomena Résumé : Solid and hollow cylindrical indium pillars with nanoscale diameters were prepared using electron beam lithography followed by the electroplating fabrication method. The microstructure of the solid-core indium pillars was characterized by scanning micro-X-ray diffraction, which shows that the indium pillars were annealed at room temperature with very few dislocations remaining in the samples. The mechanical properties of the solid pillars were characterized using a uniaxial microcompression technique, which demonstrated that the engineering yield stress is ∼9 times greater than bulk and is ∼1/28 of the indium shear modulus, suggesting that the attained stresses are close to theoretical strength. Microcompression of hollow indium nanopillars showed evidence of brittle fracture. This may suggest that the failure mode for one of the most ductile metals can become brittle when the feature size is sufficiently small. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007459 [article] Fabrication, structure and mechanical properties of indium nanopillars [texte imprimé] / Gyuhyon Lee, Auteur ; Ju-Young Kim, Auteur ; Arief Suriadi Budiman, Auteur . - 2011 . - pp. 1361–1368. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 4 (Fevrier 2010) . - pp. 1361–1368 Mots-clés : Plastic  deformation  X-ray  diffraction  Compression  test  Electroplating  Yield  phenomena Résumé : Solid and hollow cylindrical indium pillars with nanoscale diameters were prepared using electron beam lithography followed by the electroplating fabrication method. The microstructure of the solid-core indium pillars was characterized by scanning micro-X-ray diffraction, which shows that the indium pillars were annealed at room temperature with very few dislocations remaining in the samples. The mechanical properties of the solid pillars were characterized using a uniaxial microcompression technique, which demonstrated that the engineering yield stress is ∼9 times greater than bulk and is ∼1/28 of the indium shear modulus, suggesting that the attained stresses are close to theoretical strength. Microcompression of hollow indium nanopillars showed evidence of brittle fracture. This may suggest that the failure mode for one of the most ductile metals can become brittle when the feature size is sufficiently small. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007459

Tensile and compressive behavior of tungsten, molybdenum, tantalum and niobium at the nanoscale / Ju-Young Kim in Acta materialia, Vol. 58 N° 7 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2355–2363 Titre : Tensile and compressive behavior of tungsten, molybdenum, tantalum and niobium at the nanoscale Type de document : texte imprimé Auteurs : Ju-Young Kim, Auteur ; Dongchan Jang, Auteur ; Julia R. Greer, Auteur Année de publication : 2011 Article en page(s) : pp. 2355–2363 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Nanoscale  plasticity  Tension  test  Compression  test  Plastic  deformation Résumé : In situ nanomechanical tests are carried out to investigate the tensile and compressive behavior of 〈0 0 1〉-oriented body-centered cubic (bcc) metals W, Mo, Ta and Nb with nanometer dimensions. We find that the strength of these metals exhibits strong size dependence. The compressive size effect in Nb, as evaluated by the log–log slope of strength vs. nanopillar diameter, is −0.93, a factor of 2.1 greater than that for the other three metals W, Mo and Ta (−0.44). In tension, however, Ta and Nb show higher size effect slopes (−0.80 and −0.77) as compared with W and Mo (−0.58 and −0.43). We also report that while the yield strength of these metals is a strong function of size, the strain-hardening behavior does not present any size-dependent trends. We further discuss the effects of strain-rate on deformation behavior and provide transmission electron microscopy analysis of microstructural evolution in the same Mo nanopillar before and after compression. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008647 [article] Tensile and compressive behavior of tungsten, molybdenum, tantalum and niobium at the nanoscale [texte imprimé] / Ju-Young Kim, Auteur ; Dongchan Jang, Auteur ; Julia R. Greer, Auteur . - 2011 . - pp. 2355–2363. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2355–2363 Mots-clés : Nanoscale  plasticity  Tension  test  Compression  test  Plastic  deformation Résumé : In situ nanomechanical tests are carried out to investigate the tensile and compressive behavior of 〈0 0 1〉-oriented body-centered cubic (bcc) metals W, Mo, Ta and Nb with nanometer dimensions. We find that the strength of these metals exhibits strong size dependence. The compressive size effect in Nb, as evaluated by the log–log slope of strength vs. nanopillar diameter, is −0.93, a factor of 2.1 greater than that for the other three metals W, Mo and Ta (−0.44). In tension, however, Ta and Nb show higher size effect slopes (−0.80 and −0.77) as compared with W and Mo (−0.58 and −0.43). We also report that while the yield strength of these metals is a strong function of size, the strain-hardening behavior does not present any size-dependent trends. We further discuss the effects of strain-rate on deformation behavior and provide transmission electron microscopy analysis of microstructural evolution in the same Mo nanopillar before and after compression. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008647