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Indentation size effectin tungsten: Quantification of geometrically necessary dislocations underneath the indentations using HR-EBSD

Javaid, Farhan and Xu, Y. and Bruder, Enrico and Durst, Karsten (2018):
Indentation size effectin tungsten: Quantification of geometrically necessary dislocations underneath the indentations using HR-EBSD.
In: Materials Characterization, ELSEVIER SCIENCE INC, USA, pp. 39-42, (142), ISSN 10445803, DOI: 10.1016/j.matchar.2018.05.016, [Article]

Abstract

During indentation testing of the low defect density crystalline materials, higher hardness values are found at lower indentation depths, which is referred to as an indentation size effect. The depth-dependence of hardness can be described by the Nix-Gao model, which is based on the concept of Geometrically Necessary Dislocations (GNDs). The underlying dislocation mechanism remains, however, unclear and requires independent measurement of GND density below the indentation. In the present work, the depth-dependency of the GND density is quantified underneath the Berkovich indentations in tungsten via high-resolution electron backscatter diffraction. There a higher GND density is found for lower indentation depths, resulting in a higher Taylor hardness for measured GND density.

Item Type: Article
Erschienen: 2018
Creators: Javaid, Farhan and Xu, Y. and Bruder, Enrico and Durst, Karsten
Title: Indentation size effectin tungsten: Quantification of geometrically necessary dislocations underneath the indentations using HR-EBSD
Language: English
Abstract:

During indentation testing of the low defect density crystalline materials, higher hardness values are found at lower indentation depths, which is referred to as an indentation size effect. The depth-dependence of hardness can be described by the Nix-Gao model, which is based on the concept of Geometrically Necessary Dislocations (GNDs). The underlying dislocation mechanism remains, however, unclear and requires independent measurement of GND density below the indentation. In the present work, the depth-dependency of the GND density is quantified underneath the Berkovich indentations in tungsten via high-resolution electron backscatter diffraction. There a higher GND density is found for lower indentation depths, resulting in a higher Taylor hardness for measured GND density.

Journal or Publication Title: Materials Characterization
Number: 142
Publisher: ELSEVIER SCIENCE INC, USA
Uncontrolled Keywords: Tungsten, Indentation size effect, Geometrically necessary dislocations, HR-EBSD, ECCI
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Physical Metallurgy
Date Deposited: 29 May 2018 10:41
DOI: 10.1016/j.matchar.2018.05.016
Funders: The authors would like to thank Dr. Graham Meaden and Dr. David Dingley from BLG Vantage for Crosscourt software support.
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