FIGURE 22 Evaporation and condensation chamber for producing nanoscale powders, which can then be compacted into nanocrystalline bulk specimens: E=evaporation crucible; LN=liquid nitrogen cold finger for condensing powder; D= device for compacting powder. From Birringer, Herr, and Gleiter.37

FIGURE 23 Hard-sphere representation of cross section through a polycrystalline aggregate. In (a), all atoms (open circles) are allocated to crystalline grains as outlined by the dotted lines. In (b), the cross-hatched circles represent atoms allocated to the grain boundary regions between neighboring grains. When the grain size is approximately 5 nm, the grain boundary volume is about equal to the crystalline volume. From Birringer, Herr, and Gleiter.37

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