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Titolo:
Plastic strain and strain gradients at very small indentation depths
Autore:
Tymiak, NI; Kramer, DE; Bahr, DF; Wyrobek, TJ; Gerberich, WW;
Indirizzi:
Univ Minnesota, Dept Chem Engn & Mat Sci, Minneapolis, MN 55455 USA Univ Minnesota Minneapolis MN USA 55455 at Sci, Minneapolis, MN 55455 USA Hysitron Inc, Minneapolis, MN 55349 USA Hysitron Inc Minneapolis MN USA 55349 tron Inc, Minneapolis, MN 55349 USA
Titolo Testata:
ACTA MATERIALIA
fascicolo: 6, volume: 49, anno: 2001,
pagine: 1021 - 1034
SICI:
1359-6454(20010402)49:6<1021:PSASGA>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
DISLOCATION NUCLEATION; SINGLE-CRYSTALS; NANOINDENTATION; HARDNESS; DEFORMATION; SURFACES; CONTACTS;
Keywords:
hardness; dislocations; yield phenomena; metallic; atomic force microscopy (AFM);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
29
Recensione:
Indirizzi per estratti:
Indirizzo: Gerberich, WW Univ Minnesota, Dept Chem Engn & Mat Sci, 151 Amundson Hall,421 WashingtonAve SE, Minneapolis, MN 55455 USA Univ Minnesota 151 AmundsonHall,421 Washington Ave SE Minneapolis MN USA 55455
Citazione:
N.I. Tymiak et al., "Plastic strain and strain gradients at very small indentation depths", ACT MATER, 49(6), 2001, pp. 1021-1034

Abstract

Plastic strains and their respective strain gradients produced by nanoindentation have been theuretically interpreted and experimentally measured at shallow indentation depths. Existing data fur (100) tungsten with four different conical tip radii varying from 85 to 5000 nm and new data for four conical tips (R = 0.5 to 20 mum) into (100) aluminum are presented. Theoretical results based on geometrically necessary dislocations and semi-empiricalexperimental continuum calculations are compared for spherical and wedge indenters. For a sharp wedge, both experimental continuum based and theoretical geometrical approaches suggest strain gradient decreasing with the increasing indentation depth, delta. In contrast, theoretical geometrical analysis for a spherical contact yields a depth independent strain gradient proportional to 1/R and continuum calculations suggest a slight increase of a strain gradient proportional to delta (1/4)/R-3/4. Both single crystals exhibit about a factor of two decrease in hardness with increasing depth. irrespective of either increasing or decreasing average strain gradients. Implications to strain gradient plasticity and indentation size effect interpretations at very shallow depths are discussed. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

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Documento generato il 05/12/20 alle ore 19:58:19