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YouTube: SEM study of slip in deformed cadmium single crystal

Predicted by Theory: YouTube: Slip by movement of whole lattice planes. Reduced Strength due to Dislocations: YouTube: Model of slip by the movement of an edge dislocation Dislocation processes in precipitation-hardened metals during in situ deformation in an HVEM

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YouTube: SEM study of slip in deformed cadmium single crystal

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  1. Predicted by Theory: YouTube: Slip by movement of whole lattice planes Reduced Strength due to Dislocations:YouTube: Model of slip by the movement of an edge dislocationDislocation processes in precipitation-hardened metals during in situ deformation in an HVEM YouTube: 3D atom dislocation YouTube: Dislocation motion along grain boundary.avi YouTube: Dislocations in motion YouTube: SEM study of slip in deformed cadmium single crystal Young Modulus and Yield Strength

  2. Materials Moments: Aaron L—Fiber-reinforced plastics Troy/Micah–Erasers Materials Moments:

  3. Plastic Deformation YouTube: 3D atom dislocation YouTube: Model of slip by the movement of an edge dislocation • YouTube: “Brass Tension Test”

  4. Real Dislocations:Dislocation processes in precipitation-hardened metals during in situ deformation in an HVEM YouTube: Dislocation motion along grain boundary.avi YouTube: Dislocations in motionYouTube: Copy of particle disl inter high t.avi

  5. Dislocation Densities Range: 103 mm-2 1010 mm-2 Many opportunities to accommodate slip Carefully solidified Metals Highly deformed Metals

  6. SEM {100} planes SEM single crystal of cadmium deforming by dislocation slip on {100} planes.

  7. f09_07_pg183 Slip in a single zinc crystal YouTube: SEM study of slip in deformed cadmium single crystal Fig. 7.9 f09_07_pg183

  8. Slip Systems: { x y z } < a b c >

  9. FCC Slip Systems f06_07_pg180 Fig. 7.6

  10. t01_07_pg180 Table 7.1

  11. (0 1 1 0) (1 0 1 0) (1 1 0 0) (0 1 1 0) (1 1 0 0) (1 0 1 0)

  12. Plastic Deformation Section 7.5: Single Crystals

  13. f07_07_pg182 Max. shear stress is on a plane 45º from the tensile stress f07_07_pg182

  14. Slip in a single crystal Free to move at critical SS f08_07_pg182 Fig. 7.8 f08_07_pg182

  15. t01_07_pg180 Table 7.1 Table 7.1

  16. Plastic Deformation Section 7.6: Polycrystalline Materials

  17. f10_07_pg186 Plastic Deformation: Slip in Polycrystalline Copper Fig. 7.1 (173x photomicrograph) f10_07_pg186

  18. Plastic Deformation:Polycrystalline Cold-worked Nickel Fig. 7.11--170x photomicrograph f11_07_pg186 Before deformation After deformation

  19. Strengthening Mechanisms Sections 7.8 – 7.13 Strengthening Metals

  20. Underlying Principle for Strengthening Metals • Dislocations facilitate plastic deformation • Inhibiting (binding, stopping, slowing) dislocation motion makes metals stronger

  21. Strengthening Metals: • Grain-size Reduction— • Polycrystalline metals

  22. Grain size reduction:Dislocation motion at a grain boundary f14_07_pg188 Fig. 7.14

  23. Grain-size reduction Dislocation Pile-ups at grain boundaries Young Modulus and Yield Strength 2:11

  24. Strengthening metals: How do we reduce grain size?

  25. Strengthening metals: It’s difficult for dislocations to move past a grain boundary The more grain boundaries, the more difficult for dislocations to move metal is strengthened How are dislocations bound in: Grain-size reduction?

  26. The key to strengthening metals… Bind Dislocations! Sorry, I can’t move right now. I’m kinda tied up

  27. Strengthening Metals: • (Ways to restrict dislocation motion) • Grain-size reduction • Solid-solution strengthening (Diffusion) • Case hardening • Alloying

  28. f16_07_pg190 Case Hardening – Hard Case w/ tough core Low-C Steels (> 0.30% C): Carburizing, Nitriding, Carbonitriding Carburized depth of 0.030” to 0.050” in 4 hours @ 1700°F City Steel Heat Treating Co.

  29. Alloy Cu-Ni Alloy http://tankiialloy.en.made-in-china.com/offer/AqCnWidOrYcV/Sell-Copper-Nickel-Alloy-Strip.html

  30. f04_07_pg178 Atoms diffuse to a location that reduces strain energy f04_07_pg178

  31. f16_07_pg190 Solid-Solution Strengthening:Smaller Substitutional Impurity Tensile strains Fig. 7.17 f16_07_pg190

  32. f16_07_pg190 Solid-Solution Strengthening:Larger Substitutional Impurity Compressive strains Fig. 7.18

  33. f16_07_pg190 2. Solid-Solution Strengthening: Interstital Impurity Fits in interstitial sites Compressive strains Fig. 7.18

  34. f16_07_pg190 2. Solid-Solution Strengthening: Interstital Impurity Fits in interstitial sites Compressive strains Fig. 7.18

  35. Strengthening metals: They seek sites near dislocations to reduce lattice strains. This stabilizes the lattice and discourages plastic deformation. How are dislocations bound in: Solid-solution strengthening?

  36. YouTube: Dislocation motion is analogous to the movement of caterpillar How Solid-Solution strengthening binds dislocations

  37. f16_07_pg190 Cu-Ni alloy: Strength & Elongation Variation with Ni content Fig. 7.16 f16_07_pg190

  38. The SECRET to strengthening metals… Bind Dislocations!

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