<i>In situ</i> characterisation of slip-band behaviour in ferrite under mechanical loading

This study investigates the behaviour of slip bands, terminated mid-grain in the ferrite grains of age-hardened stainless steel, under different conditions, to understand their dislocation activity and response to varying loads. The full Nye lattice curvature tensor was measured in situ using high-resolution electron backscatter diffraction (HR-EBSD) to estimate the total geometrically necessary dislocation (GND) density and individual mobile and immobile dislocation activity at the slip-band scale. We found that slip bands primarily consist of edge dislocations, marked by a ‘blooming zone’ at their tip, indicating significant shear deformation and loss of mobile dislocations. The blooming zone expands as the load increases while the slip-band thickness remains constant. Coupled with the correlation between mobile and immobile dislocations within the loaded slip bands observed in situ , we observed that the dislocation activities at the slip bands were mainly from immobile edge dislocations to maintain the geometrical distortion of the slip band.