1. last lecture Introduction to materials science and engineering Atoms / electron configuration

2. today Bonding in solids Structure of crystal solids

3. Bonding Forces and Energies distance r

4. The Periodic Table METALS NONMETALS INTERMEDIATE increasing electronegativity

5. Ionic Bonding Covalent Bonding Ionic Bonding Covalent Bonding e.g. sodium chloride e.g. methane

6. Metallic Bonding

7. Bonding Energies low high

8. Crystalline Structures

9. amorphouscrystalline

10. Example: Glass quartz (crystalline) quartz glass (amorphous) Si 4+ O 2- glass (amorphous)

11. Crystalline Structures simple cubic body-centered cubic (bcc) bcc fcc

12. Hexagonal Crystal Structures hcp unit cell

13. Stacking Sequence of Close-Packed Structures first plane A first plane A and second plane B first plane A, second plane B and third plane C: fcc first plane A, second plane B and third plane A: hcp

14. FCC and BCC Solid Sphere Model fcc unit cell bcc unit cell R R = atomic radius a = unit cell length / lattice constant a a

15. Crystalline Structures of Materials

16. Lattice Parameters

17. Crystal Systems

19. How to define a direction Vector of convenient length (pass through origin) Project the vector to the axes (and measure in a, b, and c) Multiply or divide these numbers by common factor to get smallest set of integers Write them down as [uvw]

20. Miller Indices: Crystallographic Directions

21. Miller Indices: Crystallographic Directions (Miller Bravais)

22. How to define a plane Plane may not include origin! Determine the intercepts with appropriate axes as a, b, and c Take reciprocals (no intercept means infinity  reciprocal of infinity = 0) Multiply or divide these numbers by common factor to get smallest set of integers Write them down as (hkl)

23. Miller Indices: Lattice Planes intersection points: 1/2 a, 1/2b, 1/2c reciprocal values: (222)

24. Defects Point defects Linear defects 2-dimensional defects

25. Point Defects self-interstitial vacancy

26. Impurity Atoms interstitial substitutional

27. Dislocations: Edge Dislocation Burgers vector inserted half plane dislocation line

28. Dislocations: Screw Dislocation Burgers vector dislocation line

29. Grain Boundaries Ni-Base Superalloy Waspalloy 50µm high-angle grain boundary (  >15°) low-angle grain boundary

30. next Properties of materials