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Depending upon (he temperaturę, pure iron can exist in three forms, namely alpha-. gamma* and delta-iron; alpha iron i$ a potymorphic form of iron which is stable betów 906 - 910 ^#C: it has a body centered cubic lattice (bcc) and is magnetic up to 768 *C. Gamma iron is a polymorphic form of iron which is stable between 910 ^#C and 1394 °C; it has a face centered cubic lattice (fcc) and is nonmagnctic (n b its rangę of stability is reduccd by the prcscncc of carbon, manganese and mckel and it is the basis of the austenite solid Solutions). Delta iron ts the polymorphic form of iron which is stable between 1394 *C and the mclting point (1538 ®C);

it has the same lattice structure as alpha iron. (19) Ali these forms are summarized in figurę 5.

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Iron is the basis for many typcs of Steel, the properties bcing achieved by the alloying of iron with carbon. nickel. chromium and ołhcr elemcnts in varymg proportions which results in materials with vastly differing mechanical and physical properties (19)

Iron is also an cssential element for all life forms. the averagc human body contaimng 4 grams of the element The majority of iron in the body is present within hemoglobin, the respiratory pigment which provides the mechamsm for the transportation of oxygcn by red blood cells. (19)