Interlocking grain boundaries

PolycrystaUine solids are composed of many interlocking small crystals (Figure 3.6b). Most metals and ceramics in their normal states are polycrystalUne. The small crystals are often called grains, especially in metallurgy. The properties of polycrystalUne materials are often dominated by the boundaries between the crystallites, called grain boundaries. 

Figure 77. Interlocking grain boundaries bridged by WB2 particles. Note the thin TiWB2 stacks in the host crystals.

Because of the interaction between the bubbles and the growing grains, the grain boundaries possess a wave-like, interlocking structure... 

Silicate grains of all sizes show interlocking boundaries rims of large pyroxene grains have ophitic textures indistinguishable from the matrix... 

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