Title: Indentation size effect: a study via the Mechanism-based Strain-Gradient plasticity theory

Authors: Y. Huang, K.C. Hwang, J. Song, H. Gao

Addresses: Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA. ' Department of Engineering Mechanics, Tsinghua University, Beijing, 10084, China. ' Department of Mechanical Science and Engineering, University of Illinois, Urbana, IL 61801, USA. ' Division of Engineering, Brown University, Providence, RI 02912, USA

Abstract: Recent micro- and nano-indentation experiments have shown strong indentation size effects at the micron and sub-micron scales. Classical plasticity theories cannot explain the indentation size effect because their constitutive models possess no intrinsic material lengths. The Mechanism-based Strain-Gradient (MSG) plasticity theory and its simplified version, the Conventional theory of Mechanism-based Strain-Gradient plasticity (CMSG), have been established from the Taylor dislocation model and have successfully explained the indentation size effect. This paper provides a review of these theories and their applications to study the indentation of face- and body-centred-cubic metals and thin films on hard or soft substrates.

Keywords: size effect; indentation; strain gradient; geometrically necessary dislocation; microindentation; nanoindentation; mechanism-based strain-gradient; MSG plasticity theory; Taylor dislocation model.

DOI: 10.1504/IJSURFSE.2007.015023

International Journal of Surface Science and Engineering, 2007 Vol.1 No.2/3, pp.156 - 179

Published online: 05 Sep 2007 *

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