Abstract: Herein,we reported the surface modification of tungsten steel(FX1020),an advanced super-hard cutting tool material,with laser-cladded diamond coatings on Cu-transition layer,pre-covered by electrochemical deposition or by laser cladding.The influence of the Cu-transition layer on the interfacial microstructures/adhesion/stress and tribological behavior was investigated with X-ray diffraction,scanning electron microscopy and conventional mechanical probes.The preliminary results show that the Cu-transition layer had a major impact.Specifically,the FCC-structured Cu-layer,forming well-defined Cu/steel interface,significantly enhanced the interfacial adhesion and decreased the interfacial stress.As expected,the laser cladded single-layer/bilayer of diamond particles,adhesively embedded in Cu-layer,displayed excellent tribological properties,including the higher hardness,stronger wear-resistance and lower friction coefficient.Besides,the 50 μm-thick diamond bilayer outperforms the 30 μm-thick single diamond layer because of the much greater wear-resistance,larger elastic modulus,more compactness and higher density of diamond particles.