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Page 4 of 37 Ye et al. J Mater Inf 2023;3:15 https://dx.doi.org/10.20517/jmi.2023.08

L ↔ Fe Ho + fcc-Fe, L ↔ Fe Ho + Fe Ho , L ↔ Fe Ho + Fe Ho, and L ↔ hcp-Ho + Fe Ho. Besides, the
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enthalpy of formation of Fe Ho was investigated , while those of Fe Ho and Fe Ho were reported .
[44]
[54]
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Kolesnichenko et al. determined the Fe-Tm binary system . Considering the review of Massalski , four
[88]
[89]
phases exist in this system. Fe Tm is formed congruently from liquid phase at 1573 K, while Fe Tm ,
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Fe Tm , and Fe Tm form by three peritectic transformation. The enthalpy of formation of Fe Tm and
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Fe Tm was studied [44,54] .
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The Fe-Tm and Fe-Ho binary systems were evaluated in Refs [19,90,91] . A reassessment of these two binary
systems was performed in our previous study , and the assessments are consistent well with the
[28]
experimental information.
Fe-Tb and Fe-Dy
The Fe-Tb binary system has been studied [92,93] . However, the determined melting temperatures show the
[93]
large experimental errors (± 50 K and about 3 at.%). Based on the experiment results , Okamoto [94]
[92]
reported the Fe-Tb binary system. Four Fe Tb , Fe Tb , Fe Tb, and Fe Tb intermetallic compounds are
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produced via the peritectic transformation at 1,585 K, 1,549 K, 1,485 K, and 1,460 K, respectively, and
Fe Tb is produced at 1,589 K by the congruent melting. A eutectic reaction (L ↔ Fe Tb +bcc-Fe) takes
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place according to the DTA results at 1,574 K.
[95]
[96]
The Fe-Dy binary system has been determined . Four Fe Dy , Fe Dy , Fe Dy, and Fe Dy intermetallic
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compounds were found [96-98] . According to the literature [96,99] , there are two congruent transformations
(L ↔ Fe Dy and L ↔ Fe Dy), two peritectic transformations (L + Fe Dy ↔ Fe Dy and
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L + Fe Dy ↔ Fe Dy), and three eutectic transformations (L ↔ Fe Dy + fcc-Fe, L ↔ Fe Dy + Fe Dy, and
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L ↔ Fe Dy + hcp-Dy).
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Ivanov et al. measured the enthalpy of mixing and the partial enthalpy of mixing of Fe, Tb, and Dy at
1,833 K . The activities of Dy in Fe-Dy alloys between 1,273 K and 1,573 K were reported . The heat
[53]
[100]
capacity, the enthalpy difference and the entropy of formation of Fe Tb and Fe Dy at low
temperature (below 300 K) were measured . Furthermore, the enthalpy of formation of Fe Tb and
[101]
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Fe Dy was measured . The enthalpy of formation of Fe Tb, Fe Tb , Fe Dy, and Fe Dy was recently
[54]
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measured to be -5.5 ± 2.4, -2.1 ± 3.1, -1.6 ± 2.9, and -5.3 ± 1.7 kJ/mol-atom , respectively. Similarly, the
[102]
enthalpy of formation of Fe Dy, Fe Dy, and Fe Dy was reported . Using ab initio calculation, the
[103]
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enthalpy of formation of Fe Dy was reported to be -7.7 kJ/mol-atom .
[44]
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The Fe-Tb and Fe-Dy binary systems were calculated by several authors [19,83,104,105] . In our previous work, a
thermodynamic reassessment of the Fe-RE (RE = Tb and Dy) systems was conducted . However, the heat
[27]
capacity curves of Fe Tb and Fe Dy show artificial break points at 120 K due to the unreasonable
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expressions of their Gibbs energies. Therefore, the Gibbs energies of Fe Tb and Fe Dy were reassessed in
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this work based on the previous calculations .
[27]
Fe-Er
Buschow and Goot investigated the Fe-Er binary phase diagram, and found Fe Er , Fe Er , Fe Er, and
[106]
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Fe Er. Meyer studied the Fe-Er binary system, but the melting temperatures of these intermetallic
[107]
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compounds determined by Meyer are much lower (about 70 K) than the results . Subsequently,
[107]
[106]
[106]
Kolesnikov et al. re-determined the Fe-Er binary system and confirmed the reported results .
[108]
[109]
Furthermore, the experimental results [106-108] were reviewed by Okamoto . The experimental results [106-108]