Metallic　nanowires　usually　exhibit　ultrahigh　strength　but　suffered　low　ductility.　Previous　studies　on　pure　metals　suggested　this　strength-ductility　trade-off　results　from　limiting　the　dislocation　activities.　However,　it　is　unclear　whether　such　deformation　model　is　valid　for　a　solid　solution　alloy　as　well.　Here,　for　the　first　time,　the　atomic-scale　deformation　process　of　AuCu　nanowires　with　size　of-16　nm　was　investigated　in　situ.　The　results　show　the　NWs　exhibit　superplasticity　(-185%)　and　high　strengths　(-2.98　GPa)　at　room　temperature.　It　was　discovered　that　superplasticity　originates　from　continuous　full　dislocation　nucleation　and　disappearance,　as　well　as　dislocation　dipole　formation　and　annihilation　etc.,　which　differ　from　the　previous　studies　in　pure　metals.　The　observed　full　dislocation　activities,　also　different　from　the　ones　in　the　previous　studies,　suggested　that,　as　the　size　of　the　metals　is　below-100　nm,　their　deformation　should　be　governed　by　partial　dislocation　and　twinning.　(c)　2021　Elsevier　Ltd.　All　rights　reserved.