Indentation size effect in tungsten: Quantification of geometrically necessary dislocations underneath the indentations using HR-EBSD
- Physical Metallurgy Division, Materials Science Department, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287 Darmstadt (Germany)
Highlights: • Revealed the dislocation structure below nanoindentations via ECCI and HR-EBSD. • Experimentally quantification of GND densities, with higher GND densities at lower depths. • Qualitative validation of the Nix-Gao model on the indentation size effect. - 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.
- OSTI ID:
- 22832986
- Journal Information:
- Materials Characterization, Journal Name: Materials Characterization Vol. 142; ISSN 1044-5803; ISSN MACHEX
- Country of Publication:
- United States
- Language:
- English
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