1. 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
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. Aaron L—Fiber-reinforced plastics
Materials Moments:
Aaron L—Fiber-reinforced plastics
Troy/Micah–Erasers
Materials Moments:
Background image:

3. Plastic Deformation YouTube: “Brass Tension Test”
YouTube: 3D atom dislocation
YouTube: Model of slip by the movement of an edge dislocation
Figure:
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 motion YouTube: Copy of particle disl inter high t.avi
Photo: Shows what looks like triple junction from one viewpoint is actually 4-point junction when viewed from different angle.

5. Dislocation Densities
Range:
103 mm 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.
Image:

7. f09_07_pg183 Slip in a single zinc crystal
f09_07_pg183.jpg
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
f06_07_pg180.jpg
Fig. 7.6

10. t01_07_pg180
t01_07_pg180.jpg
Table 7.1

11. ( )
( )
( )
( )
( )
( )

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.jpg
f07_07_pg182

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

15. t01_07_pg180
t01_07_pg180.jpg
Table 7.1
Table 7.1

16. Polycrystalline Materials
Plastic Deformation
Section 7.6:
Polycrystalline Materials

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

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

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.jpg
f14_07_pg188
Fig. 7.14

23. Grain-size reduction Young Modulus and Yield Strength 2:11
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:
How are dislocations bound in:
Grain-size reduction?
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

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

29. Alloy
Cu-Ni Alloy
Cu-Ni Alloy

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

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

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

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

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

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

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

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

38. The SECRET to strengthening metals…
Bind Dislocations!