Metal　composites　have　attracted　great　interest　for　the　combination　of　high　strength　and　high　electrical　conductivity.　We　take　the　Cu-3　wt.%　Cr　composite　as　a　model　system　to　reveal　the　structure-property　relations　in　a　large　range　of　drawing　strains　(eta),　and　propose　the　strengthening　mechanism　during　cold　drawing.　At　small　and　moderate　drawing　strains,　the　incoherent　and　semi-coherent　interfaces　are　effective　barriers　for　dislocation　motion　and　pile-up.　The　mechanical　behaviors　are　described　well　by　the　Hall-Petch　relation.　The　work　hardening　at　eta　＜　4.5　is　the　direct　consequence　of　the　grain　refinement　and　the　increasing　density　of　phase　boundaries,　which　can　be　well　modelled　by　a　linear　rule　of　mixture.　Deviation　is　observed　at　eta　＞　4.5,　when　the　strength　gradually　reaches　a　plateau.　Microstructural　analysis　reveals　that　further　refinement　can　hardly　occur　at　high　drawing　strains　due　to　the　dynamic　recovery　process.　Another　characteristic　of　the　turning　point　is　the　structural　homogenization,　i.e.　the　mechanical　alloy　induced　inter-mixing　and　the　full　coherency.　The　transition　of　the　interface　coherency　is　clearly　identified　by　both　electron　diffraction　and　high　resolution　transmission　electron　microscopy.　The　structural　homogenization　at　the　interface　may　alleviate　the　interfacial　blockage　to　the　dislocation　slipping,　indicating　the　existence　of　an　interfacial　strength　limit.　The　linear　rule　of　mixture　is　modified　to　account　for　this　effect　at　eta　＞　4.5.　The　complete　mechanical　behavior　of　the　Cu-3　wt.%　Cr　composite　is　captured　by　a　piece-wise　function.　(C)　2015　Elsevier　B.V.　All　rights　reserved.