NATURE OF MATERIALS - Materials for Civil and Construction Engineers - page 61

(a)

(b) (c)

FIGURE 2.9 Common lattice structures for metals: (a) face center cubic (FCC)
(b) body center cubic (BCC), and (c) hexagonal close pack (HCP).

T ABLE 2.3 Lattice Structure of Metals

Crystal Atomic Crystal Atomic

Metal Structure Radius (nm) Metal Structure Radius

(nm)

Aluminum FCC 0.1413 Molybdenum BCC 0.1363

Cadmium HCP 0.1490 Nickel FCC 0.1246

Chromium BCC 0.1249 Platinum FCC 0.1387

Cobalt HCP 0.1253 Silver FCC 0.1445

Copper FCC 0.1278 Tantalum BCC 0.1430

Gold FCC 0.1442 Titanium HCP 0.1445

Iron BCC 0.1241 Tungsten BCC 0.1371

Lead FCC 0.1750 Zinc HCP 0.1332

and HCP structures and 8 for BCC structures. This can be confirmed by exam-
ination of Figure 2.9. The atomic packing factor (APF) is the fraction of the
volume of the unit cell that is occupied by the atoms of the structure:

volume of atoms in the unit cell
total unit volume of the cell

APF = (2.2)