Solidification chill zone

Solidification. When the ingot or casting solidifies, there are three main possible microstructures that form (see Figure 7.5). We will describe here only the final structures the thermodynamics of the liquid-solid phase transformation have been described previously in Chapter 2. The outside layer of the ingot is called the chill zone and consists of a thin layer of equiaxed crystals with random orientation. 

T.F. Bower and M.C. Flemings. Formation of the chill zone in ingot solidification. Trans. TMS-AIME, 239 216-219, 1967. 

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