Effects of size on the mechanical response of metallic glasses investigated through in situ TEM bending and compression experiments / C.Q. Chen in Acta materialia, Vol. 58 N° 1 (Janvier 2010)  

Public ISBD [article]  inActa materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 189–200 Titre : Effects of size on the mechanical response of metallic glasses investigated through in situ TEM bending and compression experiments Type de document : texte imprimé Auteurs : C.Q. Chen, Auteur ; Y.T. Pei, Auteur ; J.T.M. De Hosson, Auteur Année de publication : 2010 Article en page(s) : pp. 189–200 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Transmission electron microscopy (TEM) Amorphous metals Mechanical properties Résumé : Quantitative bending and compression tests on micropillars made of two different amorphous alloys, with tip diameters ranging from 93 to 645 nm, are performed in situ in a transmission electron microscope (TEM). Under microcompression each pillar shows an intermittent plastic flow accommodated by inhomogeneous shear banding. However, the individual shear banding events are strongly size-dependent, i.e. in larger pillars the deformation is controlled by nucleation of shear bands, but in smaller pillars it becomes propagation-controlled. On the other hand, the yield stress is essentially size-independent. Microbending tests show further advantages by amplifying size effects and minimizing artifacts. An interesting finding is that by microbending, a switch from highly inhomogeneous to fully homogeneous deformation is observed at an experimentally accessible size regime near 200 nm, whereas it is not accessible under microcompression, even at a sub-100 nm scale. These size effects are well interpreted by a micromechanical model, leading to a deformation map in the stress-size space. A physical picture of nanoscale shear localization process is also provided. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005928 [article] Effects of size on the mechanical response of metallic glasses investigated through in situ TEM bending and compression experiments [texte imprimé] / C.Q. Chen, Auteur ; Y.T. Pei, Auteur ; J.T.M. De Hosson, Auteur . - 2010 . - pp. 189–200. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 189–200 Mots-clés : Transmission electron microscopy (TEM) Amorphous metals Mechanical properties Résumé : Quantitative bending and compression tests on micropillars made of two different amorphous alloys, with tip diameters ranging from 93 to 645 nm, are performed in situ in a transmission electron microscope (TEM). Under microcompression each pillar shows an intermittent plastic flow accommodated by inhomogeneous shear banding. However, the individual shear banding events are strongly size-dependent, i.e. in larger pillars the deformation is controlled by nucleation of shear bands, but in smaller pillars it becomes propagation-controlled. On the other hand, the yield stress is essentially size-independent. Microbending tests show further advantages by amplifying size effects and minimizing artifacts. An interesting finding is that by microbending, a switch from highly inhomogeneous to fully homogeneous deformation is observed at an experimentally accessible size regime near 200 nm, whereas it is not accessible under microcompression, even at a sub-100 nm scale. These size effects are well interpreted by a micromechanical model, leading to a deformation map in the stress-size space. A physical picture of nanoscale shear localization process is also provided. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005928

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