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

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 size effect (ISE), which can be rationalized based on GNDs. The mechanisms, however, are still under debate. Due plane strain condition during wedge indentation, dislocations cross sections underneath indents could analyzed Nye tensor and lattice rotations determined using transmission Kikuchi diffraction. depend indent confirming different hardness regimes bilinear ISE reported recently. For shallow indents, rather localized at tip indent, while with increasing volume expands; subgrains distinct rays increased density form. At larger depths, indentation-induced deformation fields exhibit characteristics similar kink-type shear stationary crack tip. Graphical abstract