Indentation size effect: large grained aluminum versus nanocrystalline aluminum-zirconium alloys

Elmustafa, A. A.; Eastman, J. A.; Rittner, M.; Weertman, J.; Stone, Donald S.

doi:10.1016/s1359-6462(00)00520-0

Cited by 44 publications

(19 citation statements)

References 12 publications

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“…doi:10. 1016/j.ijsolstr.2006.05.009 From an experimental perspective, most attention on size effects in miniaturization has been given to strengthening effects in metals, whereby micro-bending experiments (Stö lken and Evans, 1998;Takahiro et al, 2000), nano-indentation experiments (Ma and Clarke, 1994;McElhaney et al, 1998;Nix and Gao, 1998;Elmustafa et al, 2000;Tymiak et al, 2001;Shan and Sitaraman, 2003;Zhao et al, 2003), torsion experiments (Fleck et al, 1994;Fleck and Hutchinson, 1997) or thin film analyses (Haque and Saif, 2003;Greer et al, 2005;Zong and Soboyejo, 2005) were the main set-ups used. In almost all cases, a pronounced strengthening has been found at decreasing specimen scale.…”

Section: Introductionmentioning

confidence: 99%

Size effects in miniaturized polycrystalline FCC samples: Strengthening versus weakening

Geers

Brekelmans

Janssen

2006

International Journal of Solids and Structures

107

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This paper focuses on a computational-experimental analysis of sample geometry dominated and grain dominated size effects in miniaturized polycrystalline FCC components, where the grain size, orientation and grain boundaries play an important role. Experimental and numerical findings elucidate the joint contribution of first-order and second-order size effects for this type of components. The intrinsic competition between the weakening and strengthening contributions resulting from these effects is commented and further analysed. It is shown that a second-order crystal plasticity model is needed to account for the simultaneous contributions of both size effects.

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Section: Introductionmentioning

confidence: 99%

Size effects in miniaturized polycrystalline FCC samples: Strengthening versus weakening

Geers

Brekelmans

Janssen

2006

International Journal of Solids and Structures

107

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“…The results obtained from indentation creep translate readily into those determined from tensile loading. At low temperature, Stone and coworkers reported that the activation volume, V * , can be measured using indentation method [349][350][351][352][353]. V * is defined as a measure of the Burger's vector (b) times the area swept out by dislocation during the process of thermal activation, the so-called ''activation area'' or A * [354].…”

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confidence: 99%

Nanocrystalline materials and coatings

Tjong

Chen

2004

Materials Science and Engineering: R: Reports

833

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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“…However, even in the cases where the dislocation activity might be limited by the overwhelming presence of grain boundaries, as is the case in nanocrystalline materials, higher strengths when probing smaller volumes have also been reported. [10] Generally, in polycrystalline materials, the grain boundaries inhibit dislocation motion, thereby requiring higher stresses to overcome these obstacles with decreasing grain size (i.e., with the increasing volume fraction of grain boundaries). However, this well-known Hall-Petch strengthening mechanism seizes in the nanocrystalline regime, where the grain sizes are below 100 nm, and the attained strengths are lower than predicted.…”

Section: Rising Starmentioning

confidence: 99%

Emergence of New Mechanical Functionality in Materials via Size Reduction

Greer

Jang

Kim

et al. 2009

Adv Funct Materials

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Julia R. Greer received her S.B. in Chemical Engineering from the Massachusetts Institute of Technology (1997) and a Ph.D. in Materials Science from Stanford University, where she worked on the nanoscale plasticity of gold with W. D. Nix (2005). She also worked at Intel Corporation in Mask Operations (2000–03) and was a post‐doctoral fellow at the Palo Alto Research Center (2005–07), where she worked on organic flexible electronics with R. A. Street. Greer is a recipient of TR‐35, Technology Review's Top Young Innovator award (2008), a NSF CAREER Award (2007), a Gold Materials Research Society Graduate Student Award (2004), and an American Association of University Women Fellowship (2003). Julia joined Caltech's Materials Science department in 2007 where she is developing innovative experimental techniques to assess mechanical properties of nanometer‐sized materials. One such approach involves the fabrication of nanopillars with different initial microstructures and diameters between 25 nm and 1 µm by using focused ion beam and electron‐beam lithography microfabrication. The mechanical response of these pillars is subsequently measured in a custom‐built in situ mechanical deformation instrument, SEMentor, comprising a scanning electron microscope and a nanoindenter. Read our interview with Prof. Greer on MaterialsViews.commagnified image

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Indentation size effect: large grained aluminum versus nanocrystalline aluminum-zirconium alloys

Cited by 44 publications

References 12 publications

Size effects in miniaturized polycrystalline FCC samples: Strengthening versus weakening

Size effects in miniaturized polycrystalline FCC samples: Strengthening versus weakening

Nanocrystalline materials and coatings

Emergence of New Mechanical Functionality in Materials via Size Reduction

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