N.K. Huang, H.L. Zhang, J.X. Chen and D.Z. Zhang, Institute of Nuclear Science and Technology, Sichuan University Chendu 610064, P.R. China.

Carbon films were deposited by r.f. magnetron sputtering on tungsten substrate followed by different irradiating processes with nitrogen and argon ions. Microanalyses were used to obtain the information of the phase, composition and chemical states of elements in the sample. It is found that Ar⁺ ion irradiation could not lead to the formation of tungsten-carbide, while N⁺ ion bombardment can induce the formation of the compounds of WCx, and at the same time, can react with tungsten to form WN phase. With an irradiating process of alternating Ar⁺ and N⁺ ions, the carbon film on tungsten substrate was transformed into tungsten-carbides one due to inducing effects. Microhardness measurements show that combined irradiation of Ar⁺ and N+ ions with mult-layer films structure can effectively increase surface microhardness of the tungsten sample.