Review: Indentation size effect, indentation cracks and microhardness measurement of brittle crystalline solids - some basic concepts and trends

Indentation size effect, indentation cracks and microhardness measurement of some brittle crystals are reviewed against the background of the existing concepts of indentation deformation of crystalline solids. Several approaches reported in the literature devoted to relationships between applied ind...

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Bibliographic Details
Published in:Crystal research and technology (1979) 2009-10, Vol.44 (10), p.1019-1037
Main Author: Sangwal, K.
Format: Article
Language:English
Subjects:
brittleness index
fracture toughness
indentation cracks
indentation size effect
microhardness
microhardness measurements
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Summary:Indentation size effect, indentation cracks and microhardness measurement of some brittle crystals are reviewed against the background of the existing concepts of indentation deformation of crystalline solids. Several approaches reported in the literature devoted to relationships between applied indentation test load P and indentation diagonal length d are applied to analyze the experimentally observed normal and reverse indentation size effect (ISE) in brittle compounds. Using typical examples of normal and reverse ISE it is shown that the indentation induced cracking model does not give load‐independent hardness and the final expression describing the experimental data for various compounds is essentially another form of the Meyer law. Analysis of experiment data on crack lengths and indentation diagonals for different indentation loads suggests that the origin of ISE is associated with the processes of formation of indentation cracks following the general concepts of fracture mechanics. The load‐independent hardness H0 may be determined reliably from plots of P /d against d of the proportional resistance model or of HV against 1/d as predicted by strain gradient plasticity theories. It was found that the load‐independent hardness of depends on crystal orientation and state of the indented surface. Finally, some comments on determination of fracture toughness and brittle index of crystals are made. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ISSN:0232-1300
1521-4079
DOI:10.1002/crat.200900385