A new synergy to overcome the strength-ductility trade-off dilemma in Al–Si–Cu alloy by micro-nano-particle complex clusters

•Nano-AlN particles modify eutectic Si of Al–9Si–3Cu alloy, from 13.18 μm to 2.96 μm.•Micro-nano-particle clusters improve simultaneously the strength and ductility of Al–9Si–3Cu alloy.•Ultimate tensile strengths and elongation of Al–9Si–3Cu alloy are increased by 23.4% and 123.1%.•After T6 heat treatment, spheroidal Si and θ′ phases can further enhance the strength.