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Ultrafine W-20wt.%Cu(W-20Cu) powders doped with 0-0.8 wt.% rare earth oxides Ce_0.8Sm_0.2O_1.9, (SDC) were synthesized by the EDTA-citrate method using ammonium meta-tungstate and copper nitrate as raw materials, and the resultant powders were pressed and sintered at 1250°C in H₂ atmosphere for 2h to obtain SDC/W-20Cu composites. Morphology of the SDC/W-20Cu powders and microstructure of the sintered SDC/W-20Cu composites were observed by SEM, and density, physical and mechanical property of sintered SDC/W-20Cu composites were also tested to investigate the influence of rare earth addition. The results show that the SDC/W-20Cu powders have irregular shape with particle size ranging from 100 to 200 nm. The addition of SDC has slight influence on the electrical conductivity, but obviously refines the grain size and improves the mechanical properties of the W-20Cu composites. The sintered SDC/W-20Cu samples have relative density above 97%. Bending strength and micro-hardness of the SDC/W-20Cu specimens are 1128MPa and 318HV with the addition of 0.6wt.% SDC, respectively, and the highest tensile strength reaches 580MPa and 258MPa at room temperature and 600°C, respectively..