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Qing (2018) The process of surface carburization and high temperature wear behavior of infiltrated W-Abstract 15 Tungsten-copper (W-Cu) composites are used as high temperature frictional 16 materials under special service conditions for electromagnetic gun rail and precision 17 guide for rolled pieces due to their good ablation resistance and electrical conductivity. 18 However, they have poor wear resistance at elevated temperatures. In this paper, surface 19 carburization method was applied on the W-20wt.%Cu composite to investigate the 20 mechanisms of carburization and its effects on the high temperature friction behavior 21 (Richard Y.Q. Fu) 2 of composite. Carburization process has been done at a temperature of 1100 o C for 30 1 hours. The obtained results showed that carburizing at 1100 °C with a dwelling time of 2 30 hours resulted into formation of a carburized layer and a dense intermediate sub-3 layer on the substrate. Also, the surface carburized layer with a thickness of about 70 4 μm composed of mixed phases of graphite, WC and W2C. The hardness of carburized 5 layer (~HV454) was significantly higher than that of substrate (HV223). Also, bending 6 and[S1] strength of the carburized W-Cu composites has been significantly improved, 7 although their electrical conductivity and tensile strength was decreased slightly. The 8 carburization mechanism of the W-Cu composites was found to be dominant by carbon 9 atom diffusion through reaction with W atoms and formation of surface liquid copper, 10 which promoted migration and diffusion of tungsten and carbon at high temperatures. 11 Average coefficients of friction and wear rate of carburized W-Cu composites are all 12 lower than these of un-carburized W-Cu composites owing to the presence of surface 13 carburized layer. Also, formation of CuWO4 at high temperatures reduced the friction 14 and wear resistance of the W-Cu composites. 15 16

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W-based alloys are currently considered promising candidates for high heat flux components in future fusion reactors. In this paper, hot pressed W-20wt.%Cu composites were treated at room temperature using a sliding friction severe deformation (SFD) process, with a moving speed of 0.2 m/s and an applied load of 500 N. Microstructural evolution of composites after the SFD treatment was evaluated and compared with that of the untreated composites. Results showed that there was a gradient structure generated and an obvious refinement in tungsten particles size in