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Slip distance model for the indentation size effect at the initiation of plasticity in ceramics and metals

Published online by Cambridge University Press:  31 January 2011

A.J. Bushby ,
T.T. Zhu  and
D.J. Dunstan
A.J. Bushby*
Affiliation:
Centre for Materials Research and Department of Materials, School of Engineering and Materials Science, Queen Mary, University of London, London, E1 4NS, United Kingdom
T.T. Zhu
Affiliation:
Centre for Materials Research and Department of Materials, School of Engineering and Materials Science, Queen Mary, University of London, London, E1 4NS, United Kingdom
D.J. Dunstan
Affiliation:
Centre for Materials Research and Department of Physics, Queen Mary, University of London, London, E1 4NS, United Kingdom
*
a) Address all correspondence to this author. e-mail: a.j.bushby@qmul.ac.uk
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Abstract

The indentation size effect, in which the contact pressure increases as the size of contact decreases, has been observed for many years for both spherical and pointed indenters. The concept of strain gradient plasticity has been used to describe this phenomenon, but it is often necessary to introduce a material length scale l* to fit experimental data. Here we present a theory based on the concept of dislocation slip distance, which naturally generates the scaling and incorporates the material parameters that influence the size effect. We compare this model with experimental data for a range of ceramics and tungsten metal and show that the yield strain and Burgers vector are the important material parameters in the indentation size effect.

Keywords

CeramicMetalNanoindentation
Type
Articles
Information
Journal of Materials Research , Volume 24 , Issue 3 , March 2009 , pp. 966 - 972
Copyright
Copyright © Materials Research Society 2009

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