18.08.2015   NUCLEAR CHEMICAL ENGINEERING

ZIRCONIUM AND HAFNIUM METAL AND ALLOYS

1.1 Phases

The phases of metallic zirconium and hafnium and their transition temperatures are listed in Table 7.2.

Zirconium and hafnium form nearly ideal solid solutions, with melting and transition temperatures between those of the pure components.

Equations for the vapor pressure of zirconium are [II]

Table 7.2 Phases of metallic zirconium and hafnium

Transition temperature, °С

Phase

Crystal system

Zirconium

Hafnium

Solid a

Hexagonal

863

1740

Solid P

Body-centered cubic

1852

2227

Liquid

4304

4603

Gas, 1 atm Reference

[111

[H4]

Table 7.3 Thermodynamic properties of metallic zirconium

Phase

Temperature range T, К

cP

Heat capacity = а + ЬТ+ c/T2, cal/(g-mol,0C)

Heat of transformation or fusion, cal/g-mol

From

To

a

1036

10-5c

Solid a

298

1136

5.463

2.144

-0.166

1136

930

Solid (3

1136

2125

5.137

1.5705

8.776

2125

4500

Liquid

8.00

—

—

Source: International Atomic Energy Agency, “Zirconium: Physico-Chemical Properties of Its Compounds and Alloys,” Atomic Energy Rev., Special Issue No. 6, 1976.