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

Aaron L—Fiber-reinforced plastics Materials Moments: Aaron L—Fiber-reinforced plastics Troy/Micah–Erasers Materials Moments: Background image: http://images.iop.org/objects/ntw/news/10/4/9/image1.jpg

Plastic Deformation YouTube: “Brass Tension Test” YouTube: 3D atom dislocation YouTube: Model of slip by the movement of an edge dislocation Figure: http://matse1.matse.illinois.edu/metals/11.gif YouTube: “Brass Tension Test”

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. https://www.llnl.gov/str/November05/gifs/Bulatov7.jpg

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

SEM {100} planes SEM single crystal of cadmium deforming by dislocation slip on {100} planes. Image: http://www.doitpoms.ac.uk/tlplib/miller_indices/uses.php?printable=1

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

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

FCC Slip Systems f06_07_pg180 f06_07_pg180.jpg Fig. 7.6

t01_07_pg180 t01_07_pg180.jpg Table 7.1

(0 1 1 0) (1 0 1 0) (1 1 0 0) (0 1 1 0) (1 1 0 0) (1 0 1 0)

Plastic Deformation Section 7.5: Single Crystals

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

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

t01_07_pg180 t01_07_pg180.jpg Table 7.1 Table 7.1

Polycrystalline Materials Plastic Deformation Section 7.6: Polycrystalline Materials

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

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

Strengthening Mechanisms Sections 7.8 – 7.13 Strengthening Metals

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

Strengthening Metals: Grain-size Reduction— Polycrystalline metals

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

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

Strengthening metals: How do we reduce grain size?

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

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

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

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 4 hours @ 1700°F f16_07_pg190.jpg City Steel Heat Treating Co.

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

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

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

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

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

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

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.

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

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

The SECRET to strengthening metals… Bind Dislocations!