Fundamentals of Materials Science and Engineering: An Integrated Approach, 3e

GTBL042-12 GTBL042-Callister-v2 August 13, 2007 18:22

12.9 Electrical Characteristics of Commercial Alloys • 471

Electrical resistivity (10

–8

Ω

• m)

50

40

30

20

10

0

0 102030 4050

Composition (wt% Ni)

Figure 12.9 Room-

temperature electrical

resistivity versus composition

for copper–nickel alloys.

Influence of Plastic Deformation

Plastic deformation also raises the electrical resistivity as a result of increased num-

bers of electron-scattering dislocations. The effect of deformation on resistivity is

also represented in Figure 12.8. Furthermore, its influence is much weaker than that

of increasing temperature or the presence of impurities.

Concept Check 12.2

The room-temperature electrical resistivities of pure lead and pure tin are 2.06×

10 −^7 and 1.11× 10 −^7 -m, respectively.

(a)Make a schematic graph of the room-temperature electrical resistivity versus

composition for all compositions between pure lead and pure tin.

(b)On this same graph schematically plot electrical resistivity versus composition

at 150◦C.

(c)Explain the shapes of these two curves, as well as any differences between them.

Hint:You may want to consult the lead-tin phase diagram, Figure 10.8.

[The answer may be found at http://www.wiley.com/college/callister (Student Companion Site).]

12.9 ELECTRICAL CHARACTERISTICS

OF COMMERCIAL ALLOYS

Electrical and other properties of copper render it the most widely used metallic

conductor. Oxygen-free high-conductivity (OFHC) copper, having extremely low

oxygen and other impurity contents, is produced for many electrical applications.

Aluminum, having a conductivity only about one-half that of copper, is also fre-

quently used as an electrical conductor. Silver has a higher conductivity than either

copper or aluminum; however, its use is restricted on the basis of cost.