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Section III: Supplemental Literature Review

Fe-Ge (Iron-Germanium) H. Okamoto

The Fe-Ge phase diagram in [Massalski2] was adopted from [1993Kat]. [2000Ger] found a new equilibrium phase Fe2Ge3 by mechanical alloying. Its peritectoid formation temperature of 580
C was observed by DTA on heating only. Figure 1 shows the Fe-Ge phase diagram of [1993Kat] with the additional Fe2Ge3 phase as reported by [2000Ger]. Table 1 shows Fe-Ge crystal structure data with the new information for the Fe2Ge3 phase.

Table 1 Phase

References 1993Kat: E. Kato and S. Nunoue, Fe-Ge (Iron-Germanium), Phase Diagrams of Binary Iron Alloys, H. Okamoto, Ed., ASM International, Materials Park, OH, 1993, p 156-160 2000Ger: K.B. Gerasimov and S.V. Pavlov, New Equilibrium Phase in the Fe-Ge System, Obtained by Mechanical Alloying, Intermetallics, 2000, 8, p 451-452

Fe-Ge crystal structure data

Composition, Pearson at.% Ge symbol

(aFe) (c Fe) a2 a1 e e¢ b g Fe6Ge5 FeGe

0-17.5 0-3.4 10-22 15.2-21.5 23.7-25.7 23.7-25.7 33.5-41 40.8-43.5 45.5 50

Fe2Ge3 FeGe2 (Ge)

60 66.7 100

cI2 cF4 cP2 cF16 hP8 cP4 hP4 hP6 … mC16 hP6 cP8 tP20 tI12 cF8

Space group

Strukturbericht designation

Prototype

Im3m  Fm3m Pm3m Fm3m P63/mmc Pm3m P63/mmc P63/mmc C2/m C2/m P6/mmm P213 P4c2 I4/mcm Fd 3m

A2 A1 B2 D03 D019 L12 B81 B82 … … B35 B20 … C16 A4

W Cu CsCl BiF3 Ni3Sn AuCu3 NiAs Ni2In … CoGe CoSn FeSi Ru2Sn3 Al2Cu C (diamond)

Weight Percent Germanium 0

10

20

30

40

50

60

70

80

100

90

1700

1538°C 1500

L

1394°C 1300

(γFe)

1100

37.5

1105°C

α2

(αFe)

912°C 900

β

928°C

ε

938.3°C

840°C

838°C 70

700

748°C

η

Tc ε'

580°C

Fe6Ge5

400°C

FeGe

530°C

α1

500

FeGe2

770°C

Fe2Ge3

Temperature, °C

1170°C 1122°C

(Ge)

300 0

Fe

10

20

30

40

50

60

70

80

90

Atomic Percent Germanium

Fig. 1 Fe-Ge phase diagram

292

Journal of Phase Equilibria and Diffusion Vol. 29 No. 3 2008

100

Ge