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Page 6 of 37 Ye et al. J Mater Inf 2023;3:15 https://dx.doi.org/10.20517/jmi.2023.08

[120]
[fcc(γ-Fe)/bcc(δ-Fe)] was not known. According to Buschow , Fe Y has two modifications, the
2
17
rhombohedral Th Zn and the hexagonal Th Ni . However, the temperature of this structure
2
2
l7
17
transformation was not reported, and thus Fe Y was treated as a single phase in this work. It was found
17 2
that the maximum solubility of Fe in hcp-Y is 1.5 at.% at 1173 K, but that of Y in fcc-Fe is not more than
0.6 at.% at 1,623 K .
[115]
The thermodynamic properties in liquid Fe-Y alloys at 1,873 K were measured [121,122] . The experimental
results show that the minimum enthalpy of mixing at 1,873 K is -8.44 kJ/mol at around 47 at.% Y. The
[121]
[122]
measured partial enthalpy of mixing of Y in liquid Fe-Y alloys in the Fe-rich part is much less negative
than the measured results .
[121]
The Gibbs energy of formation of Fe Y was measured , and then the enthalpy of formation of Fe Y was
[54]
17 2
17 2
deduced. The Gibbs energies of formation of Fe Y , Fe Y , Fe Y, and Fe Y were studied between 893 K
[123]
3
23 6
2
17 2
and 1,271 K.
Dariel et al. studied experimentally the specific heat and the Curie temperature of Fe Y by using differential
2
scanning calorimetry . However, Dariel et al. did not report the specific heat data but only gave the Curie
[124]
[125]
[124]
temperature of Fe Y to be 535 K . The heat capacity of Fe Y was reported at low temperature (below
17 2
2
300 K). The activities of Fe and Y were determined at 1,473 K and 1,573 K.
[126]
Thermodynamic optimization of the Fe-Y binary system was performed , and the calculated results are in
[127]
[115]
accordance with the reported data . However, the calculated thermodynamic properties show significant
deviations from the reported data , and Fe Y is produced by the peritectic reaction rather than the
[121]
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congruent reaction, which was determined by Domagala et al. . Later, several authors [128-130] re-optimized
[115]
the Fe-Y binary system. Unfortunately, the relevant thermodynamic parameters were not published [128-130] .
Combining the reported experimental data and the calculations, Kardelass et al. used two different models
to optimize the Fe-Y binary system . Combining with the reported results [114-119] and thermodynamic
[131]
calculations [127-131] , Saenko et al. optimized the new thermodynamic parameters of this binary system . The
[132]
calculations are reasonably accordant with the experimental results. However, the calculations [131,132] show
[132]
considerable homogeneity ranges of Y Fe and YFe , which are not confirmed by the reported experimental
2
6
23
[133]
results. The calculations show that the temperature of L ↔ hcp-Y + Fe Y is inconsistent with the reported
2
[121]
data , and the partial enthalpy of mixing of Fe is inconsistent with the data . Besides, the measured heat
[115]
capacity of Fe Y [125] was not considered in the calculations at low temperature (10-300 K). Therefore, the
[133]
17 2
Fe-Y binary system needs to be reassessed.
THERMODYNAMIC CALCULATION
Thermodynamic model
The Gibbs energy of solution phase φ (including liquid, fcc, bcc, and hcp) in the Fe-Tb, Fe-Dy, Fe-Er, Fe-Lu,
and Fe-Y binary systems is described as: