Class 6 CHE 333
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Transcript of Class 6 CHE 333
Class 6 CHE 333
Phase Diagrams Continued
Prov08
Copper Zinc Phase Diagram
Peritectic reaction Liquid + solid 1 -> solid 2. Eutectoid reaction Solid 1 -> solid 2 + solid 3Maximum solid solubilty of zinc in copper is 38% at around 450C
1085C
420C
Substitutional Solid SolubiltyHow much one element will dissolve in another is determined by the Hume Rothery rules
1. Atomic radii should be within 15% of each other
2 Crystal structure should be the same for each element for good solubility
3 Electronegativities should be similar.
4 The valences of the atoms should be similar.
Good solubility Cu –Ni, Cu-Au; Cu r=0.128A, Ni r=0.125, Au r=0.144Crystal structure Ti- HCP, Al - FCCPoor soluility Na-Cl Na electronegativity 0.9, Cl 3.0Valences – Zn 2+, Cu 1+Only indicate solubility from these rules.
DOES NOT APPLY TO THE ELEMENTS H,C,O,N,B THESE FORM INTERSTITIALSOLID SOLUTIONS.
Iron Carbon Phase Diagram
SteelsEutectoidS1 -> S2 + S3-> + F e3C
PeritecticS1+L -> S2 + L ->
Fe3C- cementiteA compound
1538C
3367 SUBLIMES
Fe - then then C 1394C
Stainless Steel Phase Diagram
Ternary phase diagram for stainless steels. In this case an isothermal section at a constanttemperature is used.
Lever Arm Rule
Determine the AMOUNTS of each phase use the Inverse Lever Arm Rule.Amount of solid = wa-wl/ws-wl
Amount of liquid = ws-wa/ws-wl
Amount of solid at 1300C is therefore 53-45 / 58-45 = 8/13 = 0.615= 61.5%
Amount of liquid at 1300C is therefore 58-53 / 58-45 = 5/13 = 0.385 = 38.5%
Change Average Composition 50%
Determine the AMOUNTS of each phase use the Inverse Lever Arm Rule.Amount of solid = wa-wl/ws-wlAmount of liquid = ws-wa/ws-wl
Amount of solid at 1300C is therefore 50-45 / 58-45 = 5/13 = 0.385= 38.5%
Amount of liquid at 1300C is therefore 58-50 / 58-45 = 8/13 = 0.615 = 61.5%
Microstructures and Composition
Lead Tin Microstructures90 %Pb 10%Sn
70% Pb 30%Sn
38.1%Pb 61.9% Sn
50%Pb 50%Sn
Lead Tin Microstructures15%Pb 85%Sn
Equiaxed Single Phase Grain Structure
Homework
• Using the Cu-Ni phase diagram, for a 50-50 Cu-Ni what are the compositions of the phases at 1400, 1300 and 1200 C and what phases would be present.
• Using the Pb- Sn phase diagram,what are the compositions for points “a,c and e” on the diagram?