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

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10.16 Ceramic Phase Diagrams • 375

(Al 2 O 3 )

Al 2 O 3 – Cr 2 O 3 Solid Solution

(Cr 2 O 3 )

0

2000

20 40

Composition (wt% Cr 2 O 3 )

Composition (mol% Cr 2 O 3 )

60 80 100

2100

2200

23000 20 40 60 80 100

4000

2275 ± 25 °C

3800

3600

Temperature (

°C)

Temperature (

°F)

2045 ± 5 °C

Liquid

Liquid + Solid Solution

Figure 10.23 The

aluminum

oxide–chromium

oxide phase diagram.

(Adapted from E. N.

Bunting, “Phase

Equilibria in the

System

Cr 2 O 3 –Al 2 O 3 ,”Bur.

Standards J.

Research,6,1931,

p. 948.)

(MgO) Composition (wt % Al 2 O 3 ) (Al 2 O 3 )

Composition (mol% Al 2 O 3 )

2800

2400

2000

1600

1200

5000

4500

4000

3500

3000

2500

2000

0

0

20 40 60 80 100

20 40 60 80

Liquid

MgO

(ss)

MgO (ss)

+

Liquid

MgAl 2 O 4 (ss)

+ Liquid

MgO (ss)

+

MgAl 2 O 4 (ss) MgAl^2 +O^4 (ss)

Al 2 O 3

MgAl 2 O 4

(ss)

Al 2 O 3

+

Liquid

Temperature (

°F)

Temperature (

°C)

Figure 10.24 The

magnesium

oxide–aluminum

oxide phase diagram;

ssdenotes solid

solution. (Adapted

from B. Hallstedt,

“Thermodynamic

Assessment of the

System

MgO–Al 2 O 3 ,”J. Am.

Ceram. Soc., 75 [6]

1502 (1992).

Reprinted by

permission of the

American Ceramic

Society.)