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Title: A model for the indentation size effect in polycrystalline alloys coupling intrinsic and extrinsic length scales
Authors: Gill, Simon P. A.
Campbell, Christopher J.
First Published: 28-Apr-2019
Publisher: Cambridge University Press (CUP), Materials Research Society
Citation: Journal of Materials Research, 2019
Abstract: The measured hardness of a metal crystal depends on a variety of length scales. Microstructural features, such as grain size and precipitate spacing, determine the intrinsic material length scale. Extrinsic (test) length scales, such as the indentation depth, lead to the indentation size effect (ISE), whereby it is typically found that smaller is stronger. Nix and Gao [J. Mech. Phys. Solids46, 411 (1998)] developed a widely used model for interpreting the ISE based on forest hardening in single crystalline pure metals. This work extends that model to consider the hardness of polycrystals and alloys, as well as introducing a finite limit to the hardness at very small extrinsic length scales. The resulting expressions are validated against data from the literature. It is shown that a reasonable estimate of the intrinsic material length scale can be extracted from a suite of hardness tests conducted across a range of indentation depths using spherical indenters of various radii.
DOI Link: 10.1557/jmr.2019.106
ISSN: 0884-2914
Embargo on file until: 28-Oct-2019
Version: Post-print
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2019, Cambridge University Press (CUP), Materials Research Society. Deposited with reference to the publisher’s open access archiving policy. (
Description: The file associated with this record is under embargo until 6 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.
Appears in Collections:Published Articles, Dept. of Engineering

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