Reversion of sub-boundaries into dense dislocations in aluminum by electric pulsing treatment

Abstract Rapid dissolution of sub-boundaries into dense dislocation arrays in electric-pulse-treated aluminum was observed using ex-situ transmission electron microscopy. This unusual increase of interior dislocations, which has rarely been observed in materials treated by conventional thermal treatments, suggests the rapid and possibly simultaneous operations of three mechanisms for sub-boundary dissolution, i.e., emission, extraction and collective migration of boundary dislocations. This phenomenon could be attributed to the enhanced dislocation mobility and the reduced obstacle to dislocation extraction by electric pulsing. This finding provides a new pathway to tailor the microstructure of metallic materials by concurrently coarsening subgrains and increasing dislocation density.