Developing　bimetallic　interfaces　with　high　interfacial　bonding　strength　is　important　for　metallic　composites　used　under　harsh　service　conditions.　However,　the　formation　of　brittle　intermetallic　compounds　is　unavoidable　for　some　interface　combinations,　resulting　in　a　significant　deterioration　of　bonding　strength.　In　this　work,　we　demonstrate　the　development　of　a　Cu　alloy/Al　alloy　interface　with　a　shear　strength　of　126±15　MPa　–　a　value　almost　twice　that　reported　in　previous　studies.　The　exceptional　interfacial　bonding　strength　is　attributed　to　a　special　interface　structure,　composed　of　brittle　intermetallic　compound　layers　connected　internally　by　dowels　of　a　metastable　Cu2Al3　phase,　achieved　via　alloy　design　and　process　control.　During　solid-liquid　composite　processing,　a　liquid　diffusion　layer　forms　at　the　interface　between　the　Cu　and　Al　alloys.　A　precursor　Cu4Al7Ni　phase　then　develops　at　the　Cu　side　and　transforms　into　a　metastable　Cu2Al3　phase　with　a　banded　structure.　Finally,　layers　of　Cu9Al4　and　CuAl2　layers　form,　which　are　fully　connected　to　the　Cu2Al3　phase.　The　banded　arrangement　of　the　Cu2Al3　phase　acts　to　block　crack　propagation　and　deflect　cracks　into　the　eutectic　layer　and　Al　alloy,　resulting　in　an　ultra-high　interfacial　bonding　strength.　This　work　demonstrates　that　high　interfacial　bonding　strength　can　be　achieved　by　tailoring　the　interface　structure　instead　of　by　decreasing　the　interface　thickness,　and　thus　paves　a　new　way　for　developing　high-performance　bimetallic　interfaces.　©　2024　Acta　Materialia　Inc.