Chapter 3-Crystal structures crystallography basics and metallic structures

Chapter 3-Crystal structures crystallography basics and metallic structures

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 3: Structures of Metals & Ceramics Questions to be addressed here. .. How do atoms arrange into solid structures? How does the density of a material depend on its structure? When do material properties vary with the sample (i.e., part) orientation? How do the crystal structures of ceramic materials differ from those for metals? What are the common arrangements of atoms in solids?
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Energy and Packing Non dense, random packing Dense, ordered packing Dense, ordered packed structures tend to have lower energies. Energy r typical neighbor bond length typical neighbor bond energy Energy r typical neighbor bond length typical neighbor bond energy
Background image of page 2
3 Materials and Packing crystalline SiO 2 atoms pack in periodic, 3D arrays Crystalline materials. .. -metals -many ceramics -some polymers atoms have no periodic packing Noncrystalline materials. .. -complex structures -rapid cooling noncrystalline SiO 2 " Amorphous " = Noncrystalline Adapted from Fig. 3.40(b), Callister & Rethwisch 3e. Adapted from Fig. 3.40(a), Callister & Rethwisch 3e. Si Oxygen typical of: occurs for:
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
c03f02 c03f02 Example of a particular crystal structure - “Body centered cubic”, or BCC Different ways to illustrate the same structure
Background image of page 4
Point Coordinates Point coordinates for unit cell center are a /2, b /2, c /2 ½ ½ ½ Point coordinates for unit cell corner are 111 5 z x y a b c 000 111
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Crystal Systems 6 Fig. 3.20, Callister & Rethwisch 3e. 7 crystal systems 14 crystal lattices Unit cell: smallest repetitive volume which contains the complete lattice pattern of a crystal. a, b, and c are the lattice constants
Background image of page 6
c03tf06 c03tf06
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Metallic Crystal Structures How can we stack metal atoms to minimize empty space? 2-dimensions 8 vs. Now stack these 2-D layers to make 3-D structures
Background image of page 8
Crystallographic Directions 9 1. Vector repositioned (if necessary) to pass through origin. 2. Read off projections in terms of unit cell dimensions a , b , and c 3. Adjust to smallest integer values 4. Enclose in square brackets, no commas [ uvw ] ex: 1, 0, ½ => 2, 0, 1 => [ 201 ] -1, 1, 1 families of directions < uvw > z x Algorithm where overbar represents a negative index [ 111 ] => y
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
c03f22 c03f22
Background image of page 10
c03prob c03prob
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
c03prob c03prob
Background image of page 12
Crystallographic Planes 13 Adapted from Fig. 3.25, Callister & Rethwisch 3e.
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Crystallographic Planes Miller Indices: Reciprocals of the (three) axial intercepts for a plane, cleared of fractions & common multiples. All parallel planes have same Miller indices.
Background image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 47

Chapter 3-Crystal structures crystallography basics and metallic structures

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online