Fe-Ti-Y (Iron-Titanium-Yttrium)

PDF / 226,580 Bytes
1 Pages / 593.972 x 792 pts Page_size
73 Downloads / 215 Views

Phase Diagram Evaluations: Section II

Fe-Ti-Y (Iron-Titanium-Yttrium) V. Raghavan

The two previous investigations of this ternary system by [1994Zen] and [1997Liu] reported isothermal sections at 500 and 600 °C respectively. These results were reviewed by [2001Rag] and [2000Rag]. Recently, [2009Gon] reported experimental results on this system at 1000 °C and presented a thermodynamic analysis.

Binary Systems There are two intermediate phases in the Fe-Ti system: Fe2Ti (C14, MgZn2-type hexagonal) and FeTi (B2, CsCl-type cubic). The Fe-Y system is characterized by the presence of four compounds: Fe2Y (C15, MgCu2type cubic), Fe3Y (Be3Nb-type rhombohedral), Fe23Y6 (Mn23Th6-type cubic) and Fe17Y2 (Ni17Th2-type hexagonal or Th2Zn17-type rhombohedral). In the Ti-Y system, there

are no intermediate phases. The terminal solid solubility is negligible.

Ternary Phase Equilibria The study of [2009Gon] presents serious discrepancies. Quoting from their paper: ‘‘The experimental results show that Fe2Ti and Fe2Y form a continuous solid solution, namely, Fe2(Y,Ti)’’. The previous results of [1994Zen] and [1997Liu] show little solubility between Fe2Ti and Fe2Y. Moreover, they form different crystal structures. [2009Gon] modeled the ‘‘continuous solid solution’’ phase with two sub-lattices, with Ti and Y sharing sites in the second sublattice. They computed two isothermal sections at 600 and 1000 °C. In none of the above sections, a continuous solid solution is seen. At 1000 °C, a large liquid ﬁeld is indicated at the Ti corner. Ti is solid at this temperature and shows little solubility for Y. In view of these serious anomalies, the results of [2009Gon] are not discussed further. The isothermal section at 500 °C from the ﬁrst investigation of this system by [1994Zen] (not presented in the earlier reviews) is redrawn in Fig.1.

References

Fig. 1 Fe-Ti-Y isothermal section at 500 °C [1994Zen]

1994Zen: L. Zeng, J. Li, X. Sun, and Y. Zhuang, Phase Equilibria in the Y-Ti-Fe System at 500 °C, Z. Metallkd., 1994, 85(9), p 625-627 1997Liu: Z. Liu, Z. Jin, and C. Xia, 873 K Isothermal Section of Phase Diagram for Y-Fe-Ti Ternary System, Scr. Mater., 1997, 37(8), p 1129-1134 2000Rag: V. Raghavan, Fe-Ti-Y (Iron-Titanium-Yttrium), J. Phase Equilib., 2000, 21(5), p 467 2001Rag: V. Raghavan, Fe-Ti-Y (Iron-Titanium-Yttrium), J. Phase Equilib., 2001, 22(5), p 577 2009Gon: W.P. Gong, T.F. Chen, D.J. Li, and Y. Liu, Thermodynamic Investigation of Fe-Ti-Y Ternary System, Trans. Nonferrous Met. Soc. China, 2009, 19, p 199-204

Journal of Phase Equilibria and Diffusion Vol. 30 No. 4 2009

397

Data Loading...