Figure 9.4Schematic

representation of thedevelopment ofmicrostructure

during theequilibrium

solidification of a;\5wt% Ni-65 wt%

Cu alloy.

Figure 9.5Schematic

representation of thedevelopment ofmicrostructure

during thenonequilibrium 1300

solidification of a35 wt% Ni-65 wt%

eu alloy.

30 40Composition (wt% Ni)

Figure 9.11 Schematicrepresentations of theequilibrium microstructures fora lead-tin alloy of compositionC, as it is cooled from theliquid-phase region.

Fignre 9.12 Schematicrepresentations of theequilibrium microstructuresfor a lead-tin alloy ofcomposition Cz as it is cooledfrom the liquid-phase region.

Figure 9.13Schematic

representations ofthe equilibrium

microstructures for alead-tin alloy of

eutectic compositionC3 above and below

the eutectictemperature.

in Figure 9.13.As the temperature is lowered, no changes occur until we reacheutectic temperature, 183°C. Upon crossing the eutectic isotherm, the liquid trforms to the two a and f3 phases. This transformation may be represented byreaction

600300

L

500

U 200 400 t~~ Cl (3 Q)

.3 B~ ~Q) Q)a.

) Eutectica.

E E~ structure 300 ~

Primary Cl

Cl + (3 (18.3wt% Sn)100 200

Figure 9.16 Schematic representations of the equilibrium microstructures for a lead-lillalloy of composition C4 as it is cooled from the liquid-phase region.

1200

~ 'Y, Auste ite~.3ro 1000Q;Q.

E 912°CQ)I-

800

............................................ " .....••••.~.~.---.,..."..---r

'Y,+ Fe3C

, I------_.+----------

I

400o(Fe)

Figure 9.24 The iron-iron carbide phase diagram. [Adapted from Binary Alloy PhaseDiagrams, 2nd edition, Vol. 1,T. B. Massalski (Editor-in-Chief), 1990. Reprinted bypermission of ASM International, Materials Park, OH.]

298 Chapter 10: Gibbs Free Energy Composition and Phase Diagrams of Binary Systems

01. kilojoules

·2. . ,. .,. .20 .30

"..'...

g '000

BOO

II ~ a.'BOO...•••

'-I (bJ (e)

Figure 10.23 Topological changes in the phase diagram for a system A-B with reg-ular solid and liquid solutions, brought about by systematic changes in the values ofns and 0". The melting temperatures of A and B are, respectively, 800 and 1200 K,and the molar entropies of melting of both components are 10 J/K. (From A. D. Pel-ton and W. T. Thompson, Prog. Solid State Chern. (1975), vol. 10, part 3, p. 119).