Chapter 9 Slides

Chapter 9 Slides - Chapter 9 Phase Diagrams Begin lectures...

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1 Chapter 9 Chapter 9 Phase Diagrams Phase Diagrams Begin lectures on Apr. 10, 08
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2 Chapter 9: Phase Diagrams Chapter 9: Phase Diagrams • Terminology • P-T diagrams for pure materials • Interpretation of Composition-T phase diagrams • Simple binary phase diagrams • Development of equilibrium microstructures on cooling in binary systems The Phase Rule: P + F = C + 2 P = number of phases – identifiable regions with distinctive structure or composition F = number of degrees of freedom of the system (T, P, C 0 ) C = the number of components (elements) in the system
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3 Phases : The physically and chemically distinct material regions which have homogeneous and identifiable structure (e.g., α , β ). Components : The elements that are present in the mixture (e.g., Al and Cu) Aluminum- Copper Alloy Definitions Definitions - - Components and Phases Components and Phases α (darker phase) β (lighter phase)
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4 Simple phase diagrams Simple phase diagrams Sketches of simple phase diagrams • Single component P-T (pressure-temperature) phase diagrams • Examples of simple binary Composition-T phase diagrams – Complete solid solution – Eutectic phase diagram – Peritectic phase diagram • Number of phases across the phase diagram
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5 P P - - T diagram for water (H T diagram for water (H 2 2 O) O) Note: H 2 O is actually a two-component system (H and O), that behaves like a one-component system. This is due to the fixed 2:1 H:O ratio in H 2 O • How is melting defined? • How is boiling defined? • Why does dry ice (CO 2 ) “smoke”, and what is the “smoke”?
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6 What do all these images have in What do all these images have in common? common? brittnay.files.wordpress.com/2007/11/fog_and_truck.jpg www.portagepool.ca/images/steam1.jpg www.windows.ucar.edu/glossary/ima ges/liquid_nitrogen_sm.jpg www.dkimages.com/discover/previews/ 853/848299.JPG www.ni- photos.jmcwd.com/clouds- blue-sky2.jpg www.nationwidesnowmaking. com/images/two.jpg updatecenter.britannica.com/eb/image?binary Id=93820&rendTypeId=4 Fog Steam room Liquid nitrogen Clouds Boiling water Making snow Condensation on mirror
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7 Cooking utensils Cooking utensils www.coopext.colostate.edu/TRA/cfs/food/IMAGE62.JPG gotethnicfoods.com/pictures/Regular/UT0002.jpg www.ehow.com/images/GlobalPhoto/Articles/2001020/IMG_1938_Full.jpg Pressure cooker Double boiler – being used to melt chocolate
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8 Phase Phase Equilibria Equilibria 0.1278 1.8 FCC Cu 0.1246 1.9 FCC Ni r (nm) Electro- negativity Crystal Structure • Both have the same crystal structure (FCC) and have similar electronegativities and atomic radii ( W. Hume – Rothery rules ) suggesting high mutual solubility. Start with a simple system (e.g., Ni-Cu solution) • Ni and Cu are totally miscible in all proportions.
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9 Ni Ni - - Cu Phase Diagram Cu Phase Diagram • Indicates phases as function of T , C o , and P .
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Chapter 9 Slides - Chapter 9 Phase Diagrams Begin lectures...

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