Microindentations on W and Mo oriented single crystals: An STM study

Stelmashenko, Nadia; Walls, Michael; Brown, L. M.; Milman, Yu.V.

doi:10.1016/0956-7151(93)90100-7

Cited by 635 publications

(295 citation statements)

References 3 publications

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“…This phenomenon is known as the indentation size effect (ISE). Recent studies of ISE have shown that this effect for single crystals is easily observed for depths less than 1 μm [8,9]. Nix and Gao developed a model, based on geometrically necessary dislocations (GND), which agrees with many microindentation results [10].…”

Section: Introductionsupporting

confidence: 53%

Decrease of Nano-hardness at Ultra-low Indentation Depths in Copper Single Crystal

et al. 2015

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In the present study, we report a detailed investigation of the unusual size effect in single crystals. For the experiments we specified the hardness in single crystalline copper specimens with different orientations ( (001), (011) and (111)) using Oliver-Pharr method. Our results indicates that with decreasing load, after the value of the hardness reached its maximum, it starts to decrease for very small indentation depths (<150 nm). For the sake of accuracy of hardness determination we have developed two AFM-based methods to evaluate contact area between tip and indented material. The proposed exact measurement of the contact area, which includes the effect of pile-up and sink-in patterns, can partially explain the strange behaviour, however, the decrease of hardness at low loads is still observed. At higher loads range the specified hardness is practically constant.

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Section: Introductionsupporting

confidence: 53%

Decrease of Nano-hardness at Ultra-low Indentation Depths in Copper Single Crystal

et al. 2015

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“…This has been experimentally confirmed in a number of investigations such as in indentation (Stelmashenko et al, 1993;Ma and Clarke, 1995;Swadener et al, 2002), in torsion (Fleck et al, 1994), and in bending (Stölken and Evans, 1998;Haque and Saif, 2003). A number of models have been proposed to model gradient hardening in metals.…”

Section: Introductionmentioning

confidence: 73%

“…This can also be concluded based on the close relationship that exists for the deformation fields under indentation and void growth (Marsh, 1964;Johnson, 1970). Since size-effects in indentation are widely observed in experiments (Stelmashenko et al, 1993;Ma and Clarke, 1995;Swadener et al, 2002), size effects must also be important in void growth as argued by Wei and Hutchinson (2003). Several researchers have investigated size-dependent void growth of single voids under hydrostatic loading (Fleck and Hutchinson, 1997;Huang et al, 2000;Fleck and Hutchinson, 2001).…”

Section: Introductionmentioning

confidence: 99%

Void growth to coalescence in a non-local material

Niordson

2008

European Journal of Mechanics - A/Solids

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-The size-effect in metals containing distributed spherical voids is analyzed numerically using a finite strain generalization of a length scale dependent plasticity theory. Results are obtained for stress-triaxialities relevant in front of a crack tip in an elastic-plastic metal. The influence of different material length parameters in a multi-parameter theory is studied, and it is shown that the important length parameter is the same as under purely hydrostatic loading. It is quantified how micron scale voids grow less rapidly than larger voids, and the implications of this in the overall strength of the material is emphasized. The size effect on the onset of coalescence is studied, and results for the void volume fraction and the strain at the onset of coalescence are presented. It is concluded that for cracked specimens not only the void volume fraction, but also the typical void size is of importance to the fracture strength of ductile materials.

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“…http://dx.doi.org/10.1016/j.commatsci.2013.06.057 such as in torsion [4], bending [5] and indentation [1]. From a modelling standpoint, gradient plasticity theories [6][7][8][9][10][11] that account for the effect of geometrically necessary dislocations (GNDs) [12,13] on plastic flow have had some success in explaining observed size effects.…”

Section: Introductionmentioning

confidence: 99%

Indentation studies in b.c.c. crystals with enhanced model of strain-gradient crystal plasticity

Demiral

Roy

2013

Computational Materials Science

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• This is the author's version of a work that was accepted for publication in the Computational Materials Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at:http://www.sciencedirect.com/science/article/pii/S0927025613004072

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Microindentations on W and Mo oriented single crystals: An STM study

Cited by 635 publications

References 3 publications

Decrease of Nano-hardness at Ultra-low Indentation Depths in Copper Single Crystal

Decrease of Nano-hardness at Ultra-low Indentation Depths in Copper Single Crystal

Void growth to coalescence in a non-local material

Indentation studies in b.c.c. crystals with enhanced model of strain-gradient crystal plasticity

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