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Fe-Sb-Sn (Iron-Antimony-Tin) V. Raghavan

[1997Pav] determined an isothermal section at 200 ⬚C for this system. This section is characterized by the absence of ternary compounds.

the NaCl-type cubic structure and has a wide range of homogeneity.

Binary Systems

Ternary Isothermal Section

The Fe-Sb phase diagram reviewed by [1993Oka1] is accepted. See also the update by [1999Oka]. There are two intermediate phases in this system: ␧, which has the NiAstype hexagonal structure, has a homogeneity range of 40 to 47 at.% Sb; and FeSb2 is a line compound and has the FeS2 (marcasite)-type orthorhombic structure [Pearson3, 1997Pav]. In the Fe-Sn system [1993Oka2], there are four intermediate phases: Fe5Sn3, Fe3Sn2, FeSn, and FeSn2. Some uncertainty exists regarding the composition and existence of the high-temperature phases of this system. At the temperature of our interest (200 ⬚C), only FeSn and FeSn2 are stable. FeSn has the CoSn-type hexagonal structure and FeSn2 has the CuAl2-type tetragonal structure. [1995Oht], during the course of their study of the Pb-Sb-Sn ternary system, experimenally investigated and also computed the Sb-Sn phase diagram. The only intermediate phase of the system ␤ has

[1997Pav] melted 43 alloys in an arc furnace under Ar atm. The alloys were annealed at 200 ⬚C for 400 h. The phase equilibria were studied by x-ray powder diffraction. The isothermal section of [1997Pav] at 200 ⬚C is redrawn in Fig. 1 to agree with the accepted binary data. The close atomic radii of Sb and Sn and similar electronic structure result in appreciable substitution of each other at constant Fe content in the Fe-Sb and Fe-Sn compounds. The extent of this solubility and the corresponding changes in the lattice parameters are listed in Table 1 from [1997Pav]. The Sb-Sn compound ␤ dissolves an insignificant amount of Fe. References 1993Oka1: H. Okamoto: Phase Diagrams of Binary Iron Alloys, ASM International, Materials Park, OH, 1993, pp. 366-70.

Fig. 1 Fe-Sb-Sn isothermal section at 200 ⬚C [1997Pav]

Journal of Phase Equilibria Vol. 22 No. 6 2001

669

Section II: Phase Diagram Evaluations Table 1 Fe-Sb-Sn crystal structure and lattice parameter data Composition, at.% Sn

Sb

Pearson symbol

Space group

Strukturbericht designation

Prototype

␧

0-20

45-24

hP4

P63/mmc

B81

NiAs

FeSn1⫺xSbx

50-40

0-10

hP6

P6/mmm

B35

CoSn

FeSb2⫺xSnx

0-11.7

66.7-55

oP6

Pnnm

C18

FeS2 (marcasite)

FeSn2⫺xSbx

66.7-51.7

0-15

tI12

I4/mcm

C16

CuAl2

Phase

1993Oka2: H. Okamoto: Phase Diagrams of Binary Iron Alloys, ASM International, Materials Park, OH, 1993, pp. 385-92. 1995Oht: H. Ohtani, K. Okuda, and K. Ishida: J. Phase Equilibria, 1995, vol. 16 (5), pp. 416-29.

670

Lattice parameter, nm a c a c a b c a c

⫽ ⫽ ⫽ ⫽ ⫽ ⫽ ⫽ ⫽ ⫽

0.4065 0.5121 0.5288 0.4420 0.5834 0.6530 0.3193 0.6542 0.5386

⫺ ⫺ ⫺ ⫺ ⫺ ⫺ ⫺ ⫺ ⫺

0.4138 0.5169 0.5274 0.4412 0.5890 0.6598 0.3265 0.6451 0.5292

1997Pav: V.V. Pavlyuk, O.I. Bodak, A. Stowinska, D.G. Kevorkov, and G.S. Dmytriv: Polish J. Chem., 1997, vol. 71, pp. 11-15. 1999Oka: H. Okamoto: