7. A simple phase diagram Triple point (Invariant point) Solid Liquid Vapor Pressure Temperature Phase boundary System: H 2 O
8. Gibb’s Phase Rule P + F = C + 2 P=number of phases C=number of components F=number of degrees of freedom (number of independent variables) Modified Gibbs Phase Rule (for incompressible systems) P + F = C + 1 Pressure is a constant variable F = C - P + 2 F = C - P + 1
9. Application of the phase rule At triple point, P=3, C=1, F=0 i.e. this is an invariant point At phase boundary, P=2, C=1, F=1 In each phase, P=1, C=1, F=2
12. Results L S L S t T L L + S T L T S S L L + S T L T S Pure Cu Cu-10%Ni Cu-20%Ni L L S Pure Ni S T Ni T Cu
13. Binary isomorphous phase diagram x x x x x x x x x x x x x x x x x x x x L+S L S Composition Temp T Cu T Ni 10 60 70 80 90 30 40 50 20 0 100 Cu Ni %Ni Cu Ni
24. T A B Wt%B L +L +L + T E C E L Proeutectic + +
25. L T A B Wt%B L +L +L + T E C E L particles
26. The Eutectoid Phase Diagram T A B Wt%B + + + E T E C E + T E , C =C E
27. T A B Wt%B + + + E T E C E Cooling of an alloy of eutectoid composition S + +
28. T A B Wt%B + + + E T E Cooling of an alloy of hypoeutectoid composition S + + Pro-eutectiod Pro-eutectiod
29. The Peritectic Phase Diagram T A B Wt%B L + L + L + P T P C P L at T P N M Note: and L will react only in a certain proportion= NP:PM L L
30. T A B Wt%B L + L + L + P T P C P L at T P N M Note: and L will react only in a certain proportion= NP:PM 10 25 85 NP:PM=1:2 60 L L L
31. T A B Wt%B L + L + L + P T P C P L at T P N M Note: and L will react only in a certain proportion= NP:PM L L L