The radiometric sectioning method was used to study diffusion of57Co along the grain boundaries of polycrystalline tungsten in the temperature range from 780 to 1980 K. AtTminus;1280 K (minus;0.35TmwhereTmis the melting point of the matrix element) the temperature dependence of the grain boundary diffusion (GBD) data exhibits a break which is analogous to the one observed for GBD in silver polycrystals. This break is most likely due to the fact that the mechanism of diffusant lsquo;lsquo;pumpingrsquo;rsquo; from the grain boundary to the bulk changes at low temperatures.
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