• Pulsed current induces an obvious electroplasticity effect in nanocrystalline Ni foils, significantly weakening the size effect for thickness-to-grain-size ratios between 300 and 1100.
• The electroplasticity effect is maximized when the current direction is parallel to the deformation direction (0° angle), leading to the greatest size-effect suppression.
• Higher peak current densities and smaller current-deformation angles enhance grain boundary activity and dislocation mobility, reducing dislocation entanglement and geometrically necessary dislocation density.
• These findings provide a pathway to improve the formability and reduce machining defects of nanocrystalline foils in micro-manufacturing applications.