Co–Fe phases

5 phases (tier A 4, liquid 1); 5 stable in a calculated diagram. Structure types are assigned only when the stored evidence supports an assignment under the stated tier rules (tier A: standard phase name; tier B: unique Materials Project + OQMD on-hull match, DFT-supported; tier C: one structure stated by the assessment's crystallographic table, assessor-stated); other phases list candidates and are marked needs_review. Stability is from phase diagrams calculated with pycalphad from the SGTE binary collection (evidence class: model).

Data: interactive registry · full JSON · Co–Fe system page · Markdown · field reference

Phases of the Co–Fe system (5)
Phase	Structure	Basis	Stability (calculated)	TDB models
BCC_A2 phase:co-fe:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 4 of 4 calculated diagram(s): 300–1810.95 K, x(Fe) 0.18484–1	6
B2_BCC phase:co-fe:bcc-b2	CsCl · B2 · cP2 · Pm-3m (221)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1810.95 K, x(Fe) 0.23523–1	2
FCC_A1 phase:co-fe:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 4 of 4 calculated diagram(s): 406.16–1777.77 K, x(Fe) 0–1	4
HCP_A3 phase:co-fe:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 4 of 4 calculated diagram(s): 300–779.98 K, x(Fe) 0–0.03623	4
LIQUID phase:co-fe:liquid	liquid	liquid	stable in 4 of 4 calculated diagram(s): 1745.93–2500 K, x(Fe) 0–1	4

BCC_A2 (Co–Fe)

Id: phase:co-fe:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stability: stable in 4 of 4 calculated diagram(s): 300–1810.95 K, x(Fe) 0.18484–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:co-fe:bcc-a2
tdb: tdb:CoFe-02Ohn.tdb:A2_BCC, tdb:CoFe-02Ohn.tdb:BCC_A2, tdb:CoFe-15Rod.tdb:BCC_A2, tdb:CoFe-17Wan.tdb:A2_BCC, tdb:CoFe-17Wan.tdb:BCC_A2, tdb:CoFe-87Fer-LB.tdb:BCC_A2

TDB models of BCC_A2 (6): PHASE and CONSTITUENT statements as written

CoFe-02Ohn.tdb: A2_BCC, type code %B, sha256 4ed3ddb5c0d6db77…

40: PHASE A2_BCC %B 2 1 3 !
41: CONST A2_BCC : CO FE : VA : !

CoFe-02Ohn.tdb: BCC_A2, type code %B, sha256 4ed3ddb5c0d6db77…

35: PHASE BCC_A2 %B 2 1 3 !
36: CONST BCC_A2 : CO FE% : VA : !

CoFe-15Rod.tdb: BCC_A2, type code %B, sha256 b439f24ad16996c6…

33: PHASE BCC_A2 %B 2 1 3 !
34: CONST BCC_A2 : CO FE% : VA : !

CoFe-17Wan.tdb: A2_BCC, type code %B, sha256 324b5028ec03d395…

37: PHASE A2_BCC %B 2 1 3 !
38: CONST A2_BCC : CO FE : VA : !

CoFe-17Wan.tdb: BCC_A2, type code %B, sha256 324b5028ec03d395…

32: PHASE BCC_A2 %B 2 1 3 !
33: CONST BCC_A2 : CO FE% : VA : !

CoFe-87Fer-LB.tdb: BCC_A2, type code %B, sha256 edf9a6fc99f8e55a…

31: PHASE BCC_A2 %B 2 1 3 !
32: CONST BCC_A2 : CO FE% : VA : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2015.03.001 Justin E. Rodriguez, Douglas M. Matson, Thermodynamic modeling of the solidification path of levitated Fe–Co alloys, Calphad 49, 87-100 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2017.06.001 J. Wang, X.-G. Lu, N. Zhu, W. Zheng, Calphad, 58, 82-100(2017).
assessment that models this phase
doi:10.1016/S1359-6454(01)00337-8 I. Ohnuma, H. Enoki, O. Ikeda, R. Kainuma, H. Ohtani, B. Sundman, K. Ishida, Acta Mater., 50, 379-93(2002).
assessment that models this phase

B2_BCC (Co–Fe)

Id: phase:co-fe:bcc-b2; status assigned
Structure: CsCl · B2 · cP2 · Pm-3m (221); type st:b2-cscl-cp2; tier A: standard phase name; confidence high
Caveat: CoFe-02Ohn.tdb: ordered phase with disordered part A2_BCC (order/disorder model)
Caveat: CoFe-17Wan.tdb: ordered phase with disordered part A2_BCC (order/disorder model)
Caveat: partitioned order/disorder model in CoFe-02Ohn.tdb also describes the disordered state
Caveat: partitioned order/disorder model in CoFe-17Wan.tdb also describes the disordered state
Stability: stable in 2 of 2 calculated diagram(s): 300–1810.95 K, x(Fe) 0.23523–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:co-fe:bcc-b2
tdb: tdb:CoFe-02Ohn.tdb:B2_BCC, tdb:CoFe-17Wan.tdb:B2_BCC

TDB models of B2_BCC (2): PHASE and CONSTITUENT statements as written

CoFe-02Ohn.tdb: B2_BCC, type code %BO, sha256 4ed3ddb5c0d6db77…

45: PHASE B2_BCC %BO 3 0.5 0.5 3 !
46: CONST B2_BCC : CO% FE : CO FE% : VA : !

CoFe-17Wan.tdb: B2_BCC, type code %BO, sha256 324b5028ec03d395…

42: PHASE B2_BCC %BO 3 0.5 0.5 3 !
43: CONST B2_BCC : CO% FE : CO FE% : VA : !

Example references (2 of 2; assessments first):

doi:10.1016/j.calphad.2017.06.001 J. Wang, X.-G. Lu, N. Zhu, W. Zheng, Calphad, 58, 82-100(2017).
assessment that models this phase
doi:10.1016/S1359-6454(01)00337-8 I. Ohnuma, H. Enoki, O. Ikeda, R. Kainuma, H. Ohtani, B. Sundman, K. Ishida, Acta Mater., 50, 379-93(2002).
assessment that models this phase

FCC_A1 (Co–Fe)

Id: phase:co-fe:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stability: stable in 4 of 4 calculated diagram(s): 406.16–1777.77 K, x(Fe) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:co-fe:fcc-a1
tdb: tdb:CoFe-02Ohn.tdb:FCC_A1, tdb:CoFe-15Rod.tdb:FCC_A1, tdb:CoFe-17Wan.tdb:FCC_A1, tdb:CoFe-87Fer-LB.tdb:FCC_A1

TDB models of FCC_A1 (4): PHASE and CONSTITUENT statements as written

CoFe-02Ohn.tdb: FCC_A1, type code %A, sha256 4ed3ddb5c0d6db77…

30: PHASE FCC_A1 %A 2 1 1 !
31: CONST FCC_A1 : CO% FE% : VA : !

CoFe-15Rod.tdb: FCC_A1, type code %A, sha256 b439f24ad16996c6…

28: PHASE FCC_A1 %A 2 1 1 !
29: CONST FCC_A1 : CO% FE% : VA : !

CoFe-17Wan.tdb: FCC_A1, type code %A, sha256 324b5028ec03d395…

27: PHASE FCC_A1 %A 2 1 1 !
28: CONST FCC_A1 : CO% FE% : VA : !

CoFe-87Fer-LB.tdb: FCC_A1, type code %A, sha256 edf9a6fc99f8e55a…

26: PHASE FCC_A1 %A 2 1 1 !
27: CONST FCC_A1 : CO% FE% : VA : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2015.03.001 Justin E. Rodriguez, Douglas M. Matson, Thermodynamic modeling of the solidification path of levitated Fe–Co alloys, Calphad 49, 87-100 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2017.06.001 J. Wang, X.-G. Lu, N. Zhu, W. Zheng, Calphad, 58, 82-100(2017).
assessment that models this phase
doi:10.1016/S1359-6454(01)00337-8 I. Ohnuma, H. Enoki, O. Ikeda, R. Kainuma, H. Ohtani, B. Sundman, K. Ishida, Acta Mater., 50, 379-93(2002).
assessment that models this phase

HCP_A3 (Co–Fe)

Id: phase:co-fe:hcp-a3; status assigned
Structure: Mg · A3 · hP2 · P6_3/mmc (194); type st:a3-mg-hp2; tier A: standard phase name; confidence high
Stability: stable in 4 of 4 calculated diagram(s): 300–779.98 K, x(Fe) 0–0.03623
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:co-fe:hcp-a3
tdb: tdb:CoFe-02Ohn.tdb:HCP_A3, tdb:CoFe-15Rod.tdb:HCP_A3, tdb:CoFe-17Wan.tdb:HCP_A3, tdb:CoFe-87Fer-LB.tdb:HCP_A3

TDB models of HCP_A3 (4): PHASE and CONSTITUENT statements as written

CoFe-02Ohn.tdb: HCP_A3, type code %A, sha256 4ed3ddb5c0d6db77…

50: PHASE HCP_A3 %A 2 1 0.5 !
51: CONST HCP_A3 : CO% FE : VA : !

CoFe-15Rod.tdb: HCP_A3, type code %A, sha256 b439f24ad16996c6…

38: PHASE HCP_A3 %A 2 1 0.5 !
39: CONST HCP_A3 : CO% FE : VA : !

CoFe-17Wan.tdb: HCP_A3, type code %A, sha256 324b5028ec03d395…

47: PHASE HCP_A3 %A 2 1 0.5 !
48: CONST HCP_A3 : CO% FE : VA : !

CoFe-87Fer-LB.tdb: HCP_A3, type code %A, sha256 edf9a6fc99f8e55a…

36: PHASE HCP_A3 %A 2 1 0.5 !
37: CONST HCP_A3 : CO% FE : VA : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2015.03.001 Justin E. Rodriguez, Douglas M. Matson, Thermodynamic modeling of the solidification path of levitated Fe–Co alloys, Calphad 49, 87-100 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2017.06.001 J. Wang, X.-G. Lu, N. Zhu, W. Zheng, Calphad, 58, 82-100(2017).
assessment that models this phase
doi:10.1016/S1359-6454(01)00337-8 I. Ohnuma, H. Enoki, O. Ikeda, R. Kainuma, H. Ohtani, B. Sundman, K. Ishida, Acta Mater., 50, 379-93(2002).
assessment that models this phase

LIQUID (Co–Fe)

Id: phase:co-fe:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 4 of 4 calculated diagram(s): 1745.93–2500 K, x(Fe) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:co-fe:liquid
tdb: tdb:CoFe-02Ohn.tdb:LIQUID, tdb:CoFe-15Rod.tdb:LIQUID, tdb:CoFe-17Wan.tdb:LIQUID, tdb:CoFe-87Fer-LB.tdb:LIQUID

TDB models of LIQUID (4): PHASE and CONSTITUENT statements as written

CoFe-02Ohn.tdb: LIQUID, type code %, sha256 4ed3ddb5c0d6db77…

25: PHASE LIQUID:L % 1 1 !
26: CONST LIQUID:L : CO FE : !

CoFe-15Rod.tdb: LIQUID, type code %, sha256 b439f24ad16996c6…

23: PHASE LIQUID:L % 1 1 !
24: CONST LIQUID:L : CO FE : !

CoFe-17Wan.tdb: LIQUID, type code %, sha256 324b5028ec03d395…

22: PHASE LIQUID:L % 1 1 !
23: CONST LIQUID:L : CO FE : !

CoFe-87Fer-LB.tdb: LIQUID, type code %, sha256 edf9a6fc99f8e55a…

21: PHASE LIQUID:L % 1 1 !
22: CONST LIQUID:L : CO FE : !

Example references (3 of 3; assessments first):

doi:10.1016/j.calphad.2015.03.001 Justin E. Rodriguez, Douglas M. Matson, Thermodynamic modeling of the solidification path of levitated Fe–Co alloys, Calphad 49, 87-100 (2015).
assessment that models this phase
doi:10.1016/j.calphad.2017.06.001 J. Wang, X.-G. Lu, N. Zhu, W. Zheng, Calphad, 58, 82-100(2017).
assessment that models this phase
doi:10.1016/S1359-6454(01)00337-8 I. Ohnuma, H. Enoki, O. Ikeda, R. Kainuma, H. Ohtani, B. Sundman, K. Ishida, Acta Mater., 50, 379-93(2002).
assessment that models this phase

Please cite

R. Arróyave, J. Saal, D. Shin, ORCHID-Registry: phase registry of binary systems (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735970
R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23736065

Also cite B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file; A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0); the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work). Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

@misc{orchid_phase_registry_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Registry: phase registry of binary systems}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735970},
  url       = {https://doi.org/10.5281/zenodo.23735970},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}