Page 192 - Materials Chemistry, Second Edition

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3.2. Metallic Structures and Properties

Figure 3.15. Representative cooling curves for an alloy, A–B. The terms LCT and UCT refer to lower and
upper critical temperatures, respectively. TA and TB designate the melting points of pure A and pure B,
respectively.

Figure 3.16. Simplified schematic of the transformation from BCC to FCC, exhibited between the three
allotropes of iron. Corner atoms have been omitted for clarity.

phases of iron and steels, present as an interstitial dopant within these lattices.
Experimental evidence shows that carbon-doped iron polymorphs are indeed inter-
stitial solid solutions. For instance, the carbon atoms in bcc ferrite are located only
on empty face-centered positions. However, very few of these positions are occu-
pied throughout the lattice, as the maximum solubility of carbon in a-Fe is only