Engineering Materials
A material is known as allotropic or polymorphic if it

Has its atoms distributed in a random pattern
Has a fixed structure under all conditions
Responds to heat treatment
Exists in several crystal forms at different temperatures

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Engineering Materials
White cast iron

Is produced by small additions of magnesium (or creium) in the ladle. Graphite is in nodular or spheroidal form and is well dispersed throughout the material
Is also known as chilled cast iron and is obtained by cooling rapidly. It is almost unmachinable
Is produced by annealing process. It is soft, tough and easily machined metal
Contains 1.7 to 3.5% carbon in Free State and is obtained by the slow cooling of molten cast iron

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