The problem of residual porosity in relation to grain growth in powder compacts is discussed. It is shown that the present diffusion theory of densification, together with Zener's relation, can account, at least qualitatively, for the residual porosity in powder compacts. Moreover, this theory brings out the physical meaning of the so-called ‘Sauerwald temperature’ phenomenon. The porosity occurring in multicomponent powder compacts, as a result of the difference in diffusivities, is also discussed.
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