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MENG 426: Metals, Alloys & Composites Experiment

This lab tutorial covers eutectic, hyper-, and hypo-alloys in the context of phase diagrams. Learn about phase transformations and microstructures in different alloy compositions.

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MENG 426: Metals, Alloys & Composites Experiment

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  1. The American University in CairoMechanical Engineering DepartmentMENG 426: Metals, Alloys & Composites Interactive MENG 426 Lab Tutorials Experiment (3) Eutectic, Hyper- & Hypo- Alloys Prepared by Eng. Moataz M. Attallah Fall 2002

  2. Outline • Introduction: Phase diagrams • Alloy systems • Invariant Reactions • Eutectic Reaction • Specimen • Results

  3. Introduction Equilibrium Diagrams • Phase Diagram: Graphical representation for the material (pure/mixture/binary alloy/tertiary alloy) within a temperature range at a range of compositions, showing the existing phases & any transformation reactions. • Equilibrium cooling: slow cooling that does not deform the structure.

  4. Phase Diagrams A B C

  5. http://mst-online.nsu.edu/mstonline/metals/Figure59.htm http://www.eng.auburn.edu/~wfgale/intro_metals/graphics/fig10_pure_fe.swf Unary Phase Diagram

  6. Isomorphous Extensive Solubility No Solubility Partial Solubility Partial SS Binary Phase Diagrams

  7. Isomorphous SystemExtensive Solid Solution Strengthening (SSS) Liquidus Solidus

  8. Solidus Solvus Terminal Solid Solution Polymorphous SystemPartial Solid Solution Strengthening (SSS) Liquidus

  9. SSS Parameters • Difference in atomic radii less than 15% • Same crystal structure • Minimal difference in electro-negativity • Same valence number

  10. Interstitial Solid Solution

  11. ISS Parameters • Existence of interstitial site that can accommodate a small atom • Interstitials are: H, C, N, O

  12. Invariant Reactions

  13. Eutectic Eutecticoid Peritectic Peritectoid Montectic Invariant Reactions • Phase transformation reactions that take place at a specific temperature and composition (zero degree of freedom). • Types:

  14. Eutectic Reaction

  15. Eutectic Microstructure

  16. rodlike lamellar acicular globular Eutectic Morphologies** Morphology means the form, shape or outward microstructure of a phase W. F. Smith

  17. Eutectic Model

  18. Specimens • Specimen (1):8.4% phosphorus content: etch or 30 seconds in aqueous ferrous chloride. • Specimen (2):4.5% phosphorus content: etch or 40 seconds in aqueous ferrous chloride, which makes a dark surface after etching. • Specimen (3):10.5% phosphorus content: etch for several seconds in a solution containing 2 parts of water/1 part ammonia solution and hydrogen peroxide.

  19. Cu-P Phase Diagram

  20. Cu-P Phase transformation

  21. Lab Report Required: • A "neat" sketch for the viewed microstructures. • Describe the phase transformation for each specimen from the liquid state to the solid state with the aid of the (Cu-Cu3P) phase diagram.

  22. Lab Report (2) Due Date Due to the 6th of October holiday, next week labs are cancelled. Lab report #2 is due in Tuesday October 8th class

  23. Questions?

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