Module 06 Structure of Crystalline Solids.pdf - Material...

Material Science and Engineering for M.E.
57017
Structure of Crystalline Solids
Prepared by:
Engr. Dexter Lyndon Sabusap

Objectives
1. Describe the difference in atomic/molecular structure between crystalline and noncrystalline
materials.
2. Draw unit cells for face-centered cubic, body-centered cubic, body-centered tetragonal, and
hexagonal closed-packed crystal structures.
3. Derive the relationships between unit edge cell length and atomic radius for face-centered
cubic, body-centered cubic, body-centered tetragonal, and hexagonal closed-packed crystal
structures.
4. Compute the densities for metals having face-centered cubic, body-centered cubic, body-
centered tetragonal, and hexagonal closed-packed crystal structures.

Crystalline Material
A crystalline material is one in which the atoms are situated in a
repeating or periodic array over large atomic distances; that is, long-
range order exists, such that upon solidification, the atoms will position
themselves in a repetitive three-dimensional pattern, in which each
atom is bonded to its nearest-neighbor atoms.