In-situ investigation on indentation response at subsurface by multi-detector inside SEM

Indentation tests create complex stress–strain states in the region beneath the indentation tip. However, it is difficult to observe the indentation responses of bulk materials. Therefore, this study presents a wedge-indentation test technology that can investigate the subsurface deformation behavior during loading and unloading inside a scanning electron microscope. In situ observations based on multiple techniques, including a secondary electron detector, electron backscatter diffraction, and digital image correlation, are realized and used to investigate the texture evolution and stress–strain behavior of monocrystalline copper in the microregion beneath the indentation tip. Indentation induces kinked slip bands along the [01‾1‾] and [011‾] directions. The maximum shear strain of 0.324 occurs at the sides of the area in direct contact with the indentation tip. The lattice rotations in three dimensions are calculated and obtained quantitatively, and the geometrically necessary dislocation density beside the contact region reaches 0.70 × 10¹⁴/m². The proposed method has considerable potential for explaining the deformation mechanisms of materials at microscale.