Size-dependent geometrically necessary dislocation structures in single-crystalline tungsten

Journal of materials research/Pratt's guide to venture capital sources, vol. 37, pp. 3646–3657

Abstract

Abstract Wedge indentation experiments were conducted to study the depth dependence of geometrically necessary dislocation (GND) structures in single-crystalline tungsten. Single-crystalline tungsten exhibits a pronounced indentation size effect (ISE), which can be rationalized based on GNDs. The dislocation mechanisms, however, are still under debate. Due to the plane strain condition during the wedge indentation, the dislocations in the cross sections underneath indents could be analyzed based on the Nye tensor and the lattice rotations determined using transmission Kikuchi diffraction. The dislocation structures depend on the size of the indent confirming the different hardness regimes and the bilinear ISE reported recently. For shallow indents, the dislocations are rather localized at the tip of the indent, while with increasing depth the dislocation volume expands; subgrains and distinct rays of increased dislocation density form. At larger depths, the indentation-induced deformation fields exhibit characteristics similar to the kink-type shear at a stationary crack tip. Graphical abstract

Authors 5

1. Jin Wang corresponding

   Karlsruhe Institute of Technology · Forschungszentrum Jülich

   Affiliation as printed

   Institute for Applied Materials, Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany

   Institute of Energy and Climate Research, Forschungszentrum Juelich GmbH, 52425, Juelich, Germany

2. LiKang Luan

   Karlsruhe Institute of Technology

   Affiliation as printed

   Institute for Applied Materials, Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany

3. Tillmann Volz

   Karlsruhe University of Applied Sciences

   Affiliation as printed

   Center of Applied Research, Karlsruhe University of Applied Sciences, 76012, Karlsruhe, Germany

   Faculty of Mechanical Engineering and Mechatronics, Karlsruhe University of Applied Sciences, 76012, Karlsruhe, Germany

4. Sabine M. Weygand

   Karlsruhe University of Applied Sciences

   Affiliation as printed

   Faculty of Mechanical Engineering and Mechatronics, Karlsruhe University of Applied Sciences, 76012, Karlsruhe, Germany

5. Ruth Schwaiger corresponding Aachen Chair of Energy Engineering Materials Faculty 5

   Karlsruhe Institute of Technology · Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Chair of Energy Engineering Materials, Faculty 5, RWTH Aachen University, 52056, Aachen, Germany

   Institute for Applied Materials, Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany

   Institute of Energy and Climate Research, Forschungszentrum Juelich GmbH, 52425, Juelich, Germany