Large elongated grains

Superplasticity is macroscopically defined as the ability of a polycrystalline material to exhibit large elongations at elevated temperatures and relatively low stresses. It is commonly found in a wide range of materials from metals to ceramics (bioceramics or high-temperature superconductors, among others) when the grain size is small enough a few micrometres for metals and less than a micron in ceramics. 

Toughness in the direction parallel to the orientation of the large elongated p-grains (whiskers). 

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